JEE Main Session 1 February 25th Shift 2 Question Paper with Answer Key

Physics

Section-A

1. Match List I with List II.

List I

(a) Rectifier

(b) Stabilizer

(c) Transformer

(d) Filter   

List II

(i) Used either for stepping up or stepping down the A.C. voltage

(ii) Used to convert A.C. voltage into D.C. voltage

(iii) Used to remove any ripple in the rectified output voltage

(iv) Used for constant output voltage even when the input voltage or load current change

Choose the correct answer form the options given below:

(a)  (a)-(ii), (b)- (i), (c)-(iv), (d)-(iii)

(b)  (a)-(ii), (b)- (iv), (c)-(i), (d)-(iii)

(c)  (a)-(ii), (b)- (i), (c)-(iii), (d)-(iv)

(d) (a)-(iii), (b)- (iv), (c)-(i), (d)-(ii)

Answer: (b)

2. Y = A sin(ωt + ϕ0) is the time – displacement equation of an SHM, At t = 0, the displacement of the particle is Y = A/2 and it is moving along negative x-direction. Then, the initial phase angle ϕ0 will be.

(a)  π/6

(b)  π/3

(c)  2π/3

(d) 5π/6

Answer: (d)

3. Two identical springs of spring constant ‘2K’ are attached to a block of mass m and to fixed support (see figure). When the mass is displaced from equilibrium position on either side, it executes simple harmonic motion. Then, time period of oscillations of this system is:

(a)    

(b)   

(c)   

(d)  

Answer: (a)

4. The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n = 2 to n = 1 state is:

(a)  194.8 nm

(b)  490.7 nm

(c)  913.3 nm

(d) 121.8 nm

Answer: (d)

5. In a ferromagnetic material below the Curie temperature, a domain is defined as:

(a)  a macroscopic region with consecutive magnetic diploes oriented in opposite direction.

(b)  a macroscopic region with zero magnetization.

(c)  a macroscopic region with saturation magnetization.

(d) a macroscopic region with randomly oriented magnetic dipoles.

Answer: (c)

6. The point A moves with a uniform speed along the circumference of a circle of radius 0.36m and cover 30° in 0.1s. The perpendicular projection ‘P’ form ‘A’ on the diameter MN represents the simple harmonic motion of ‘P’. The restoring force per unit mass when P touches M will be:

(a)  100 N

(b)  50 N

(c)  9.87 N

(d) 0.49 N

Answer: (c)

7. The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491 nm is 0.710 V. When the incident wavelength is changed to a new value, the stopping potential is 1.43 V. The new wavelength is:

(a)  400 nm

(b)  382 nm

(c)  309 nm

(d) 329 nm

Answer: (b)

8. A charge ‘q’ is placed at one corner of a cube as shown in figure. The flux of electrostatic field through the shaded area is:

(a)  q/48ε0

(b)  q/8ε0

(c)  q/24ε0

(d) q/4ε0

Answer: (c)

9. A sphere of radius ‘a’ and mass ‘m’ rolls along horizontal plane with constant speed v0. It encounters an inclined plane at angle θ and climbs upward. Assuming that it rolls without slipping how far up the sphere will travel (along the incline)?

(a)   

(b)   

(c)   

(d)  

Answer: (d)

10. Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter 0.1 μm. If the diameter of the pinhole is slightly increased, it will affect the diffraction pattern such that:

(a)  its size decreases, but intensity increases

(b)  its size increases, but intensity decreases

(c)  its size increases, and intensity increases

(d) its size decreases, and intensity decreases

Answer: (a)

11. An electron of mass me and a proton of mass mp = 1836 me are moving with the same speed. The ratio of their de Broglie wavelength  will be:

(a)  918

(b)  1836

(c)  1/1836

(d) 1

Answer: (b)

12. Thermodynamic process is shown below on a P-V diagram for one mole of an ideal gas. If V2 = 2V1 then the ratio of temperature T2/T1 is:

(a)  1/√2

(b)  1/2

(c)  2

(d) √2

Answer: (d)

13. A stone is dropped from the top of a building. When it crosses a point 5m below the top, another stone starts to fall from a point 25m below the top, both stones reach the bottom of building simultaneously. The height of the building is: [Take g = 10 m/s2]

(a)  45 m

(b)  35 m

(c)  25 m

(d) 50 m

Answer: (a)

14. If a message signal of frequency ‘fm‘ is amplitude modulated with a carrier signal of frequency ‘fc‘ and radiated through an antenna, the wavelength of the corresponding signal in air is:

[Given, C is the speed of electromagnetic waves in vacuum/air]

(a)   

(b)   

(c)  c/fm

(d) c/fc

Answer: (d)

15. Given below are two statements:

Statement I: In a diatomic molecule, the rotational energy at a given temperature obeys Maxwell’s distribution.

Statement II: In a diatomic molecule, the rotational energy at a given temperature equals the translational kinetic energy for each molecule.

In the light of the above statements, choose the correct answer from the options given below:

(a)  Both statement I and statement II are false.

(b)  Both statement I and statement II are true.

(c)  Statement I is false but statement II is true.

(d) Statement I is true but statement II is false.

Answer: (d)

16. An electron with kinetic energy K1 enters between parallel plates of a capacitor at an angle ‘α’ with the plates. It leaves the plates at angle ‘β’ with kinetic energy K2. Then the ratio of kinetic energies K1 : K2 will be:

(a)    

(b)   

(c)   

(d)  

Answer: (b)

17. An LCR circuit contains resistance of 110 Ω and a supply of 220 V at 300 rad/s angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by 45°. If on the other hand, only inductor is removed the current leads by 45° with the applied voltage. The rms current flowing in the circuit will be:

(a)  2.5 A

(b)  2 A

(c)  1 A

(d) 1.5 A

Answer: (b)

18. For extrinsic semiconductors: when doping level is increased;

(a)  Fermi–level of p and n-type semiconductors will not be affected.

(b)  Fermi–level of p-type semiconductors will go downward and Fermi–level of n-type semiconductor will go upward.

(c)  Fermi–level of both p–type and n–type semiconductors will go upward for T > TFK and downward for T < TFK, where TF is Fermi temperature.

(d) Fermi–level of p-type semiconductor will go upward and Fermi–level of n–type semiconductors will go downward.

Answer: (b)

19. The truth table for the following logic circuit is:

(a)    

(b)   

(c)   

(d)  

Answer: (d)

20. If e is the electronic charged, c is the speed of light in free space and h is planck’s constant, the quantity  has dimensions of :

(a)  [LC1]

(b)  [M0 L0 T0]

(c)  [M L T0]

(d) [M L T1]

Answer: (2)

Section-B

21. The percentage increase in the speed of transverse waves produced in a stretched string if the tension is increased by 4% will be _______%.

Answer: (2)

22. Two small spheres each of mass 10 mg are suspended from a point by threads 0.5 m long. They are equally charged and repel each other to a distance of 0.20 m. Then charge on each of the sphere is  The value of ‘a’ will be________. [Take g = 10 m/s2]

Answer: (20)

23. The peak electric field produced by the radiation coming from the 8 W bulb at a distance of 10 m is  The efficiency of the bulb is 10% and it is a point source. The value of x is ___.

Answer: (2)

24. Two identical conducting spheres with negligible volume have 2.1nC and -0.1nC charges, respectively. They are brought into contact and then separated by a distance of 0.5 m. The electrostatic force acting between the spheres is _______× 109 [Given :  SI unit]

Answer: (36)

25. The initial velocity v1 required to project a body vertically upward from the surface of the earth to just reach a height of 10R, where R is the radius of the earth, may be described in terms of escape velocity ve such that  The value of x will be _______.

Answer: (20)

26. A current of 6A enters one corner P of an equilateral triangle PQR having 3 wires of resistance 21Ω each and leaves by the corner R. The currents i1 in ampere is______.

Answer: (2)

27. The wavelength of an X-ray beam is 10 Å. The mass of a fictitious particle having the same energy as that of the X-ray photons is The value of x is _______.

Answer: (10)

28. A reversible heat engine converts one- fourth of the heat input into work. When the temperature of the sink is reduced by 52 K, its efficiency is doubled. The temperature in Kelvin of the source will be_______.

Answer: (208)

29. Two particles having masses 4g and 16g respectively are moving with equal kinetic energies. The ratio of the magnitudes of their linear momentum is n:2. The value of n will be_____.

Answer: (1)

30. If  the angle between  is θ(0° < θ < 360°). The value of ‘θ’ will be _______.

Answer: (180)

Chemistry

Section-A

1. Given below are two statements:

Statement I: The identification of Ni2+ is carried out by dimethylglyoxime in the presence of NH4OH

Statement II: The dimethylglyoxime is a bidentate neutral ligand.

In the light of the above statements, choose the correct answer from the options given below:

(a)  Both statement I and statement II are true

(b)  Both statement I and statement II are false

(c)  Statement I is false but statement II is true

(d) Statement I is true but statement II is false

Answer: (d)

2. Carbylamine test is used to detect the presence of a primary amino group in an organic compound. Which of the following compounds is formed when this test is performed with aniline?

Answer: (b)

3. The correct order of bond dissociation enthalpy of halogen is:

(a)  F2 > Cl2 > Br2 > I2

(b)  Cl2 > F2 > Br2 >I2

(c)  Cl2 > Br2 > F2 >I2

(d) I2 > Br2 > Cl2 > F2

Answer: (c)

4. Which one of the following statements is FALSE for hydrophilic sols?

(a)  These sols are reversible in nature

(b)  The sols cannot be easily coagulated

(c)  They do not require electrolytes for stability

(d) Their viscosity is of the order of that of H2O

Answer: (d)

5. Water does not produce CO on reacting with

(a)  C3H8

(b)  C

(c)  CH4

(d) CO2

Answer: (d)

6. What is ‘X’ in the given reaction?

Answer: (a)

7. If which of the following orders the given complex ions are arranged correctly with respect to their decreasing spin only magnetic moment?

(i) [FeF6]3

(ii) [Co(NH3)6]3+

(iii) [NiCl4] 2

(iv) [Cu(NH3)4]2+

(a)  (ii) > (i) > (iii) > (iv)

(b)  (iii) > (iv) > (ii) > (i)

(c)  (ii) > (iii) > (i) > (iv)

(d) (i) > (iii) > (iv) > (ii)

Answer: (d)

8. The major product of the following reaction:

Answer: (d)

9. The correct sequence of reagents used in the preparation of 4-bromo-2-nitroethyl benzene from benzene is:

(a)  CH3COCl/AlCl3, Br2/AlBr3, HNO3/H2SO4, Zn/HCl

(b)  CH3COCl/AlCl3, Zn-Hg/HCl, Br2/AlBr3, HNO3/H2SO4

(c)  Br2/AlBr3, CH3COCl/AlCl3, HNO3/H2SO4, Zn/HCl

(d) HNO3/H2SO4, Br2/AlCl3, CH3COCl/AlCl3, Zn-Hg/HCl

Answer: (b)

10. The major components of German Silver are:

(a)  Cu, Zn and Mg

(b)  Ge, Cu and Ag

(c)  Zn, Ni and Ag

(d) Cu, Zn and Ni

Answer: (d)

11. The method used for the purification of Indium is:

(a)  Van Arkel method

(b)  Vapour phase refining

(c)  Zone refining

(d) Liquation

Answer: (c)

12. Which of the following is correct structure of α-anomer of maltose

Answer: (d)

13. The major product of the following reaction is:

(a)  CH3CH2CH2CHO

(b)  CH3CH2CH=CH―CHO

(c)  CH3CH2CH2CH2CHO

(d) 

Answer: (c)

14. The correct order of acid character of the following compounds is:

(a)  II > III > IV > I

(b)  III > II > I > IV

(c)  IV > III > II > I

(d) I > II > III > IV

Answer: (a)

15. Which among the following species has unequal bond lengths?

(a)  XeF4

(b)  SiF4

(c)  BF4

(d) SF4

Answer: (d)

16. Given below are two statements:

Statement I: α and β forms of sulphur can change reversibly between themselves with slow heating or slow cooling.

Statement II: At room temperature the stable crystalline form of sulphur is monoclinic sulphur.

In the light of the above statements, choose the correct answer from the options given below.

(a)  Both statement I and statement II are false

(b)  Statement I is true but statement II is false

(c)  Both statement I and statement II are true

(d) Statement I is false but statement II is true

Answer: (b)

17. Correct statement about the given chemical reaction is:

(a)  Reaction is possible and compound (A) will be a major product.

(b)  The reaction will form a sulphonated product instead of nitration.

(c)  NH2 group is ortho and para directive, so product (B) is not possible.

(d) Reaction is possible and compound (B) will be the major product.

Answer: ()

18. Which of the following compound is added to the sodium extract before addition of silver nitrate for testing of halogens?

(a)  Nitric acid

(b)  Sodium hydroxide

(c)  Hydrochloric acid

(d) Ammonia

Answer: (a)

19. Given below are two statements:

Statement I: The pH of rain water is normally ~5.6.

Statement II: If the pH of rain water drops below 5.6, it is called acid rain.

In the light of the above statements, choose the correct answer from the option given below.

(a)  Statement I is false but Statement II is true

(b)  Both statement I and statement II are true

(c)  Both statement I and statement II are false

(d) Statement I is true but statement II is false

Answer: (b)

20. The solubility of Ca(OH)2 in water is:

[Given: The solubility product of Ca(OH)2 in water = 5.5 × 106]

(a)  1.1 × 106

(b)  1.77 × 106

(c)  1.7 × 102

(d) 1.11 × 102

Answer: (d)

Section-B

21. If a compound AB dissociates to the extent of 75% in an aqueous solution, the molality of the solution which shows a 2.5 K rise in the boiling point of the solution is ______molal.

Answer: (3)

22. The spin only magnetic moment of a divalent ion in aqueous solution (atomic number 29) is ____BM.

Answer: (2)

23. The number of compound/s given below which contain/s —COOH group is ______

(a)  Sulphanilic acid

(b)  Picric acid

(c)  Aspirin

(d) Ascorbic acid

Answer: (a)

24. The unit cell of copper corresponds to a face centered cube of edge length 3.596 Å with one copper atom at each lattice point. The calculated density of copper in kg/m3 is ______.

Answer: (9077)

25. Consider titration of NaOH solution versus 1.25 M oxalic acid solution. At the end point following burette readings were obtained.

(i) 4.5 mL (ii) 4.5 mL (iii) 4.4 mL (iv) 4.4 mL (v) 4.4 mL

If the volume of oxalic acid taken was 10.0 ml. then the molarity of the NaOH solution is ____M. (Rounded-off to the nearest integer)

Answer: (6)

26. Electromagnetic radiation of wavelength 663 nm is just sufficient to ionize the atom of metal A. The ionization energy of metal A in kJ mol1 (Rounded off to the nearest integer)

[h=6.63 × 1034Js, c = 3.00 × 108 ms1, NA=6.02 × 1023 mol1]

Answer: (180)

27. The rate constant of a reaction increases by five times on increasing temperature from 27°C to 52° The value of activation energy in kJ mol1 is ______.

(Rounded off to the nearest integer)

[R=8.314 J K1 mol1]

Answer: (52)

28. Copper reduces into NO and NO2 depending upon the concentration of HNO3 in solution. (Assuming fixed [Cu2+] and PNO = PNO2), the HNO3 concentration at which the thermodynamic tendency for reduction of into NO and NO2 by copper is same is 10x

The value of 2x is ______. (Rounded-off to the nearest integer)

[Given    and at 298 K,  ]

Answer: (4)

29. Five moles of an ideal gas at 293 K is expanded isothermally from an initial pressure of 2.1 MPa to 1.3 MPa against a constant external 4.3 MPa. The heat transferred in this process is ____kJ mol1. (Rounded-off of the nearest integer)

[Use R = 8.314 J mol1 K1]

Answer: (15)

30. Among the following, the number of metal/s which can be used as electrodes in the photoelectric cell is _____(Integer answer).

(a)  Li

(b)  Na

(c)  Rb

(d) Cs

Answer: (a)

Mathematics

Section-A

1. A plane passes through the points A(1,2,3), B(2,3,1) and C(2,4,2). If O is the origin and P is (2,–1,1), then the projection of vector  on this plane is of length:

(a)   

(b)   

(c)   

(d)   

Answer: (c)

2. The contrapositive of the statement “If you will work, you will earn money” is:

(a)  If you will not earn money, you will not work

(b)  You will earn money, if you will not work

(c)  If you will earn money, you will work

(d)  To earn money, you need to work

Answer: (a)

3. If α, β∈ R are such that 1 – 2i (here i2 = –1) is a root of z2 + αz + β = 0, then (α – β) is equal to:

(a)  7

(b)  −3

(c)  3

(d)  −7

Answer: (d)

4. If  then

(a)   

(b)   

(c)  I2 + I4, I3 + I5, I4 + I6 are in A.P.

(d)  I2 + I4, I3 + I5, I4 + I6 are in G.P.

Answer: (b)

5. If for the matrix,  AAT = I2, then t he value of α4 + β4 is:

(a)  1

(b)  3

(c)  2

(d)  4

Answer: (a)

6. Let x denote the total number of one-one functions from a set A with 3 elements to a set B with 5 elements and y denote the total number of one-one functions from the set A to the set A × B. Then:

(a)  y = 273x

(b)  2y = 91x

(c)  y = 91x

(d)  2y = 273x

Answer: (b)

7. If the curve x2 + 2y2 = 2 intersects the line x + y = 1 at two points P and Q, then the angle subtended by the line segment PQ at the origin is:

(a)    

(b)   

(c)   

(d)   

Answer: (a)

8. The integral  is equal to:

(where c is a constant of integration)

(a)  loge|x2 + 5x – 7| +c

(b)   

(c)  4loge|x2 + 5x – 7| + c

(d)   

Answer: (c)

9. A hyperbola passes through the foci of the ellipse  and its transverse and conjugate axes coincide with major and minor axes of the ellipse, respectively. If the product of their eccentricities is one, then the equation of the hyperbola is:

(a)    

(b)   

(c)  x2 – y2 = 9

(d)   

Answer: (b)

10. is equal to:

(a)  1

(b)  1/3

(c)  1/2

(d)  1/4

Answer: (c)

11. In a group of 400 people, 160 are smokers and non-vegetarian; 100 are smokers and vegetarian and the remaining 140 are non-smokers and vegetarian. Their chances of getting a particular chest disorder are 35%, 20% and 10% respectively. A person is chosen from the group at random and is found to be suffering from chest disorder. The probability that the selected person is a smoker and non-vegetarian is:

(a)  7/45

(b)  8/45

(c)  14/45

(d)  28/45

Answer: (d)

12. The following system of linear equations

2x + 3y + 2z = 9

3x + 2y + 2z = 9

x – y + 4z = 8

(a)  does not have any solution

(b)  has a unique solution

(c)  has a solution (α, β, γ) satisfying α + β2 + γ3 = 12

(d)  has infinitely many solutions

Answer: (b)

13. The minimum value of  where a, x ∈ R and a > 0, is equal to:

(a)   

(b)  a + 1

(c)  2a

(d)  2√a

Answer: (d)

14. A function f(x) is given by  then the sum of the series  is equal to:

(a)  19/2

(b)  49/2

(c)  39/2

(d)  29/2

Answer: (c)

15. Let α and β be the roots of x2 – 6x – 2 = 0. If an = αn – βn for n ≥ 1, then the value of  is:

(a)  4

(b)  1

(c)  2

(d)  3

Answer: (c)

16. Let A be a 3 × 3 matrix with det(A) = 4. Let Ri denote the ith row of A. If a matrix B is obtained by performing the operation R2→ 2R2 + 5R3 on 2A, then det(B) is equal to:

(a)  64

(b)  16

(c)  80

(d)  128

Answer: (a)

17. The shortest distance between the line x – y = 1 and the curve x2 = 2y is:

(a)  1/2

(b)  0

(c)  1/2√2

(d)  1/√2

Answer: (c)

18. Let A be a set of all 4-digit natural numbers whose exactly one digit is 7. Then the probability that a randomly chosen element of A leaves remainder 2 when divided by 5 is:

(a)  1/5

(b)  2/9

(c)  97/297

(d)  122/297

Answer: (c)

19. is equal to:

(a)  75/56

(b)  65/56

(c)  56/33

(d)  65/33

Answer: (b)

20. If 0 < x, y < π and cos x + cos y – cos (x + y) = 3/2, then sin x + cos y is equal to:

(a)   

(b)   

(c)   

(d)    

Answer: (a)

Section-B

21. If  exists and is equal to b, then the value of a – 2b is _________.

Answer: (5)

22. A line is a common tangent to the circle (x – 3)2 + y2 = 9 and the parabola y2 = 4x. If the two points of contact (a, b) and (c, d) are distinct and lie in the first quadrant, then 2(a+c) is equal to ______.

Answer: (9)

23. The value of  is ______.

Answer: (19)

24. If the remainder when x is divided by 4 is 3, then the remainder when (2020 + x)2022 is divided by 8 is ______.

Answer: (1)

25. A line L passing through origin is perpendicular to the lines

If the co-ordinates of the point in the first octant on L2 at the distance of √17 from the point of intersection of L and L1 are (a, b, c), then 18(a + b + c) is equal to ______.

Answer: (44)

26. A function f is defined on [–3, 3] as

where [x] denotes the greatest integer ≤ x. The number of points, where f is not differentiable in (–3, 3) is ______.

Answer: (5)

27. If the curves x = y4 and xy = k cut at right angles, then (4k)6 is equal to ______.

Answer: (4)

28. The total number of two digit numbers ‘n’, such that 3n + 7n is a multiple of 10, is ______.

Answer: (45)

29. Let  If the area of the parallelogram whose adjacent sides are represented by the vectors is 8√3 square units, then  is equal to________.

Answer: (2)

30. If the curve y = y(x) represented by the solution of the differential equation (2xy2 – y)dx + xdy = 0, passes through the intersection of the lines, 2x – 3y = 1 and 3x + 2y = 8, then |y(1)| is equal to ______.

Answer: (1)

JEE Main Session 1 February 25th Shift 1 Question Paper with Answer Key

Physics

Section-A

1. A 5V battery is connected across the points X and Y. Assume D1 and D2 to be normal silicon diodes. Find the current supplied by the battery if the + ve terminal of the battery is connected to point X.

(a)  ~0.86 A

(b)  ~0.5 A

(c)  ~0.43 A

(d) ~1.5 A

Answer: (c)

2. A solid sphere of radius R gravitationally attracts a particle placed at 3R from its centre with a force F1. Now a spherical cavity of radius R/2 is made in the sphere (as shown in figure) and the force becomes F2. The value of F1: F2 is:

(a)  41 : 50

(b)  36 : 25

(c)  50 : 41

(d) 25 : 36

Answer: (a)

3. A student is performing the experiment of resonance column. The diameter of the column tube is 6 cm. The frequency of the tuning fork is 504 Hz. Speed of the sound at the given temperature is 336 m/s. The zero of the metre scale coincides with the top end of the resonance column tube. The reading of the water level in the column when the first resonance occurs is:

(a)  13 cm

(b)  14.8 cm

(c)  16.6 cm

(d) 18.4 cm

Answer: (b)

4. A diatomic gas, having  is heated at constant pressure. The ratio dU : dQ : dW

(a)  3 : 7 : 2

(b)  5 : 7 : 2

(c)  5 : 7 : 3

(d) 3 : 5 : 2

Answer: (b)

5. Statement I: A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz. The bandwidth requirement for the signal is 4 kHz.

Statement II: The side band frequencies are 1002 kHz and 998 kHz.

In the light of the above statements, choose the correct answer from the options given below:

(a)  Both statement I and statement II are false

(b)  Statement I is false but statement II is true

(c)  Statement I is true but statement II is false

(d) Both statement I and statement II are true

Answer: (d)

6. The current (i) at time t = 0 and t = ∞ respectively for the given circuit is:

(a)   

(b)   

(c)   

(d)   

Answer: (c)

7. Two satellites A and B of masses 200 kg and 400 kg are revolving round the earth at height of 600 km and 1600 km respectively.

If TA and TB are the time periods of A and B respectively then the value of TB − TA:

[Given: Radius of earth = 6400 km, mass of earth = 6×1024 kg]

(a)  4.24 × 102 s

(b)  3.33 × 102 s

(c)  1.33 × 103 s

(d) 4.4 × 103 s

Answer: (c)

8. An engine of a train, moving with uniform acceleration, passes the signal post with velocity u and the last compartment with velocity v. The velocity with which middle point of the train passes the signal post is:

(a)   

(b)    

(c)   

(d)  

Answer: (c)

9. A proton, a deuteron and an α particle are moving with the same momentum in a uniform magnetic field. The ratio of magnetic forces acting on them is _______ and their speeds are in the ratio______.

(a)  2 : 1 : 1 and 4 : 2 : 1

(b)  1 : 2 : 4 and 2 : 1 :1

(c)  1 : 2 : 4 and 1 : 1 : 2

(d) 4 : 2 : 1 and 2 : 1 : 1

Answer: (a)

10. Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: When a rod lying freely is heated, no thermal stress is developed in it.

Reason R: On heating, the length of the rod increases

In the light of the above statements, choose the correct answer from the options given below:

(a)  A is true but R is false

(b)  Both A and R are true and R is the correct explanation of A

(c)  Both A and R are true but R is NOT the correct explanation of A

(d) A is false but R is true

Answer: (c)

11. In an octagon ABCDEFGH of equal side, what is the sum of

(a)   

(b)   

(c)   

(d)  

Answer: (a)

12. Two radioactive substances X and Y originally have N1 and N2 nuclei respectively. Half-life of X is half of the half-life of Y. After three half-lives of Y, numbers of nuclei of both are equal. The ratio N1/N2 will be equal to:

(a)  8/1

(b)  1/8

(c)  3/1

(d) 1/3

Answer: (a)

13. Match List-I with List-II:

List-I                                             List-II

(a) h(Planck’s constant)                (i) [MLT1]

(b) E(Kinetic energy)                    (ii) [ML2T1]

(c) V(Electric potential)                (iii) [ML2T2]

(d) P (Linear momentum)             (iv) [ML2I1T3]

Choose the correct answer from the options given below:

(a)  (a) → (ii), (b) →(iii), (c) → (iv), (d) → (i)

(b)  (a) →(i), (b) → (ii), (c) →(iv), (d) → (iii)

(c)  (a) → (iii), (b) → (ii), (c) →(iv), (d) →(i)

(d) (a) → (iii), (b) → (iv), (c) →(ii), (d) →(i)

Answer: (a)

14. The pitch of the screw gauge is 1 mm and there are 100 divisions on the circular scale. When nothing is put in between the jaws, the zero of the circular scale lines 8 divisions below the reference line. When a wire is placed between the jaws, the first linear scale division is clearly visible while 72nd division on circular scale coincides with the reference line. The radius of the wire is:

(a)  1.64 mm

(b)  1.80 mm

(c)  0.82 mm

(d) 0.90 mm

Answer: (c)

15. If the time period of a two meter long simple pendulum is 2 s, the acceleration due to gravity at the place where pendulum is executing S.H.M. is:

(a)  2π2ms2

(b)  16 m/s2

(c)  9.8 ms2

(d) π2 ms2

Answer: (a)

16. An α particle and a proton are accelerated from rest by a potential difference of 200 V. After this, their de Broglie wavelengths are λα and λp The ratio λpα is:

(a)  8

(b)  2.8

(c)  3.8

(d) 7.8

Answer: (b)

17. Given below are two statements: one is labelled as Assertion A and the other is labelled as reason R.

Assertion A: The escape velocities of planet A and B are same. But A and B are of unequal masses.

Reason R: The product of their masses and radii must be same. M1R1 = M2R2

In the light of the above statements, choose the most appropriate answer from the options given below:

(a)  Both A and R are correct but R is NOT the correct explanation of A

(b)  A is correct but R is not correct

(c)  Both A and R are correct and R is the correct explanation of A

(d) A is not correct but R is correct

Answer: (b)

18. The angular frequency of alternating current in a L-C-R circuit is 100 rad/s. The components connected are shown in the figure. Find the value of inductance of the coil and capacity of condenser.

(a)  0.8 H and 250 μF

(b)  0.8 H and 150 μF

(c)  1.33 H and 250 μF

(d) 1.33 H and 150 μF

Answer: (a)

19. Two coherent light sources having intensities in the ratio 2x produce an interference pattern. The ratio  will be:

(a)   

(b)   

(c)   

(d)  

Answer: (c)

20. Magnetic fields at two points on the axis of a circular coil at a distance of 0.05 m and 0.2 m from the centre are in the ratio 8 : 1. The radius of coil is ______

(a)  0.15 m

(b)  0.2 m

(c)  0.1 m

(d) 1.0 m

Answer: (c)

Section-B

21. The same size images are formed by a convex lens when the object is placed at 20 cm or at 10 cm from the lens. The focal length of a convex lens is ______ cm.

Answer: (15)

22. The electric field in a region is given by  The ratio of flux of reported field through the rectangular surface of area 0.2 m2 (parallel to y-z plane) to that of the surface of area 0.3 m2 (parallel to x-z plane) is a : 2, where a = ________

[Here i, j and k are unit vectors along x, y and z-axes respectively]

Answer: (1)

23. 512 identical drops of mercury are charged to a potential of 2 V each. The drops are joined to form a single drop. The potential of this drop is ____ V.

Answer: (128)

24. The potential energy (U) of a diatomic molecule is a function dependent on r (interatomic distance) as  Where, a and b are positive constants. The equilibrium distance between two atoms will (2α/β)a/b. Where a =_______

Answer: (1)

25. A small bob tied at one end of a thin string of length 1m is describing a vertical circle so that the maximum and minimum tension in the string are in the ratio 5 : 1. The velocity of the bob at the highest position is ______ m/s. (take g = 10 m/s2)

Answer: (5)

26. In a certain thermodynamic process, the pressure of a gas depends on its volume as kV3. The work done when the temperature changes from 1000 C to 300°C will be ______ nR, where n denotes number of moles of a gas.

Answer: (50)

27. In the given circuit of potentiometer, the potential difference E across AB (10 m length) is larger than E1 and E2 as well. For key K1 (closed), the jockey is adjusted to touch the wire at point J1 so that there is no deflection in the galvanometer. Now the first battery (E1) is replaced by the second battery (E2) for working by making K1 open and E2 The galvanometer gives then null deflection at J2. The value of E1/E2 is the smallest fraction of a/b, Then the value of a is ____.

Answer: (1)

28. A monoatomic gas of mass 4.0 u is kept in an insulated container. Container is moving with a velocity 30 m/s. If container is suddenly stopped then change in temperature of the gas (R=gas constant) is x/3R. Value of x is ______.

Answer: (3600)

29. A coil of inductance 2 H having negligible resistance is connected to a source of supply whose voltage is given by V = 3t volt. (where t is in second). If the voltage is applied when t = 0, then the energy stored in the coil after 4 s is _______ J.

Answer: (144)

30. A transmitting station releases waves of wavelength 960 m. A capacitor of 256 μF is used in the resonant circuit. The self inductance of coil necessary for resonance is _____ × 10–8

Answer: (10)

Chemistry

Section-A

1. Ellingham diagram is a graphical representation of:

(a)  ΔG vs T

(b)  (ΔG – TΔS) vs T

(c)  ΔH vs T

(d) ΔG vs P

Answer: (a)

2. Which of the following equations depicts the oxidizing nature of H2O2?

(a)  Cl2 + H2O2 → 2HCl + O2

(b)  KlO4 + H2O2 → KlO3 + H2O + O2

(c)  2l + H2O2 + 2H+ → I2 + 2H2O

(d) I2 + H2O2 + 2OH– → 2I– + 2H2O + O2

Answer: (c)

3. In Freundlich adsorption isotherm at moderate pressure, the extent of adsorption (x/m) is directly proportional to Px. The value of x is:

(a)  ∞

(b)  1

(c)  zero

(d) 1/n

Answer: (d)

4. According to molecular orbital theory, the species among the following that does not exist is:

(a)  He2

(b)  He2+

(c)  O22

(d) Be2

Answer: (d)

5. Identify A in the given chemical reaction.

Answer: (d)

6. Given below are two statements:

Statement-I: CeO2 can be used for oxidation of aldehydes and ketones.

Statement-II: Aqueous solution of EuSO4 is a strong reducing agent.

(a)  Statement I is true, statement II is false

(b)  Statement I is false, statement II is true

(c)  Both Statement I and Statement II are false

(d) Both Statement I and Statement II are true

Answer: (d)

7. The major product of the following chemical reaction is:

(a)  (CH3CH2CO)2O

(b)  CH3CH2CHO

(c)  CH3CH2CH3

(d) CH3CH2CH2OH

Answer: (b)

8. Complete combustion of 1.80 g of an oxygen-containing compound (CxHyOz) gave 2.64 g of CO2 and 1.08 g of H2 The percentage of oxygen in the organic compound is:

(a)  63.53

(b)  51.63

(c)  53.33

(d) 50.33

Answer: (c)

9. The correct statement about B2H6 is:

(a)  All B–H–B angles are of 120°.

(b)  Its fragment, BH3, behaves as a Lewis base.

(c)  Terminal B–H bonds have less p-character when compared to bridging bonds.

(d) The two B–H–B bonds are not of the same length.

Answer: (c)

10. In which of the following pairs, the outermost electronic configuration will be the same?

(a)  Fe2+ and Co+

(b)  Cr+ and Mn2+

(c)  Ni2+ and Cu+

(d) V2+ and Cr+

Answer: (b)

11. Which statement is correct?

(a)  Buna-S is a synthetic and linear thermosetting polymer

(b)  Neoprene is an addition copolymer used in plastic bucket manufacturing

(c)  Synthesis of Buna-S needs nascent oxygen

(d) Buna-N is a natural polymer

Answer: (c)

12. Given below are two statements:\

Statement-I: An allotrope of oxygen is an important intermediate in the formation of reducing smog.

Statement-II: Gases such as oxides of nitrogen and Sulphur present in the troposphere contribute to the formation of photochemical smog.

(a)  Statement I and Statement II are true

(b)  Statement I is true about Statement II is false

(c)  Both Statement I and Statement II are false

(d) Statement I is false but Statement II is true

Answer: (c)

13. The plots of radial distribution functions for various orbitals of hydrogen atom against ‘r’ are given below:

(a)  (4)

(b)  (2)

(c)  (1)

(d) (3)

Answer: (a)

14. Which of the glycosidic linkage galactose and glucose is present in lactose?

(a)  C-1 of glucose and C-6 of galactose

(b)  C-1 of galactose and C-4 of glucose

(c)  C-1 of glucose and C-4 of galactose

(d) C-1 of galactose and C-6 of glucose

Answer: (b)

15. Which one of the following reactions will not form acetaldehyde?

Answer: (a)

16. Which of the following reaction/s will not give p-amino azobenzene?

(a)  2 only

(b)  1 and 2

(c)  3 only

(d) 1 only

Answer: (a)

17. The hybridization and magnetic nature of [Mn(CN)6]4– and [Fe(CN)6]3–, respectively are:

(a)  d2sp3 and paramagnetic

(b)  sp3d2 and paramagnetic

(c)  d2sp3 and diamagnetic

(d) sp3d2 and diamagnetic

Answer: (a)

18. Identify A and B in the chemical reaction.

Answer: (d)

19. Compound(s) which will liberate carbon dioxide with sodium bicarbonate solution is/are:

(a)  2 and 3 only

(b)  1 only

(c)  2 only

(d) 3 only

Answer: (a)

20. The solubility of AgCN in a buffer solution of pH = 3 is x. The value of x is: [Assume: No cyano complex is formed; Ksp(AgCN) = 2.2 × 10–16 and Ka(HCN) = 6.2 × 10–10]

(a)  0.625 × 106

(b)  1.6 × 106

(c)  2.2 × 106

(d) 1.9 × 106

Answer: (d)

Section-B

21. The reaction of cyanamide, NH2CN(s) with oxygen was run in a bomb calorimeter and ΔU was found to be –742.24 kJ mol–1. The magnitude of ΔH298 for the reaction  is ______ kJ.  (Rounded off to the nearest integer). [Assume ideal gases and R = 8.314 J mol–1 K–1]

Answer: (741 kj/mol)

22. In basic medium CrO42– oxidizes S2O32– to form SO24 and itself changes into Cr(OH)4. The volume of 0.154 M CrO42– required to react with 40 mL of 0.25 M S2O32– is ______ mL. (Rounded-off to the nearest integer)

Answer: (173 mL)

23. For the reaction, aA + bB → cC + dD, the plot of log k vs 1/T is given below:

The temperature at which the rate constant of the reaction is 10–4s–1 is ________ K. [Rounded off to the nearest integer)

[Given: The rate constant of the reaction is 10–5s–1 at 500 K]

Answer: (526 K)

24. 0.4g mixture of NaOH, Na2CO3 and some inert impurities was first titrated with N/10HCl using phenolphthalein as an indicator, 17.5 mL of HCl was required at the end point. After this methyl orange was added and titrated. 1.5 mL of the same HCl was required for the next end point. The weight percentage of Na2CO3 in the mixture is ______. (Rounded-off to the nearest integer)

Answer: (3%)

25. The ionization enthalpy of Na+ formation from Na(g) is 495.8 kJ mol–1, while the electron gain enthalpy of Br is –325.0 kJ mol–1. Given the lattice enthalpy of NaBr is –728.4 kJ mol–1. The energy for the formation of NaBr ionic solid is (–)_____ × 10–1 kJ mol–1.

Answer: (5576 kJ)

26. Consider the following chemical reaction.

The number of sp2 hybridized carbon atom(s) present in the production is __________.

Answer: (7)

27. A car tire is filled with nitrogen gas at 35 psi at 27°C. It will burst if pressure exceeds 40 psi. The temperature in °C at which the car tyre will burst is ______. (Rounded-off to the nearest integer)

Answer: (69.85°C 70°C)

28. Among the following, the number of halide(s) which is/are inert to hydrolysis is ______.

(a)  BF3

(b)  SiCl4

(c)  PCl5

(d) SF6

Answer: (1)

29. 1 molal aqueous solution of an electrolyte A2B3 is 60% ionised. The boiling point of the solution at 1 atm is _____ K. (Rounded-off to the nearest integer). [Given Kb for (H2O) = 0.52 K kg mol–1]

Answer: (375 K)

30. Using the provided information in the following paper chromatogram:

The calculated Rf value of A ______ × 10–1.

Answer: (4)

Mathematics

Section-A

1. The coefficients a, b and c of the quadratic equation, ax2 + bx + c = 0 are obtained by throwing a dice three times. The probability that this equation has equal roots is :

(a)  1/54

(b)  1/72

(c)  1/36

(d) 5/216

Answer: (d)

2. Let α be the angle between the lines whose direction cosines satisfy the equations l +m – n = 0 and l2 + m2 – n2 = 0. Then the value of sin4 α + cos4 α is :

(a)  3/4

(b)  1/2

(c)  5/8

(d) 3/8

Answer: (c)

3. The value of the integral

is

(a)   

(b)   

(c)   

(d)  

Answer: (c)

4. A man is observing, from the top of a tower, a boat speeding towards the tower from a certain point A, with uniform speed. At that point, the angle of depression of the boat with the man’s eye is 30° (Ignore man’s height). After sailing for 20 seconds towards the base of the tower (which is at the level of water), the boat has reached point B, where the angle of depression is 45°. Then the time taken (in seconds) by the boat from B to reach the base of the tower is :

(a)  10(√3 – 1)

(b)  10√3

(c)  10

(d) 10(√3+1)

Answer: (d)

5. If 0 < θ,  and   then:

(a)  xyz = 4

(b)  xy – z = (x + y)z

(c)  xy + yz + zx = z

(d) xy + z = (x+y)z

Answer: (d)

6. The equation of the line through the point (0,1,2) and perpendicular to the line  is:

(a)   

(b)   

(c)   

(d)  

Answer: (a)

7. The statement A (B A) is equivalent to:

(a)  A (A ᐱ B)

(b)  A (A ᐯ B)

(c)  A (A B)

(d) A (A B)

Answer: (b)

8. The integer k, for which the inequality x2 – 2(3k – 1)x + 8k2 – 7 > 0 is valid for every x in R is :

(a)  3

(b)  2

(c)  4

(d) 0

Answer: (a)

9. A tangent is drawn to the parabola y2 = 6x which is perpendicular to the line 2x + y =1. Which of the following points does NOT lie on it?

(a)  (0, 3)

(b)  (−6, 0)

(c)  (4, 5)

(d) (5, 4)

Answer: (d)

10. Let f, g: N→N such that f(n + 1)= f(n) + f(1) for all n ∈ N and g be any arbitrary function. Which of the following statements is NOT true ?

(a)  f is one-one

(b)  If fog is one-one, then g is one-one

(c)  If g is onto, then fog is one-one

(d) If f is onto, then f(n) = n for all n ∈ Nc

Answer: (c)

11. Let the lines (2 – i) z = (2 + i)  and (2 + i)z + (I – 2) − 4i = 0, (here i2 = −1) be normal to a circle C. If the line   is tangent to this circle C, then its radius is:

(a)  3/√2

(b)  3√2

(c)  3/2√2

(d) 1/2√2

Answer: (c)

12. All possible values of θ ∈ [0, 2π] for which sin2θ + tan 2θ > 0 lie in

(a)    

(b)   

(c)   

(d)  

Answer: (b)

13. The image of the point (3,5) in the line x – y + 1 = 0, lies on :

(a)  (x – 2)2 + (y – 4) 2 =4

(b)  (x – 4)2 + (y + 2) 2 =16

(c)  (x – 4)2 + (y – 4) 2 = 8

(d) (x – 2) 2 + (y – 2) 2 =12

Answer: (a)

14. If Rolle’s theorem holds for the function f(x) = x3 – ax2 + bx – 4, x ∈ [1, 2] with  then ordered pair (a, b) is equal to :

(a)  (–5, 8)

(b)  (5, 8)

(c)  (5, –8)

(d) (–5, –8)

Answer: (b)

15. If the curves,  intersect each other at an angle of 90°, then which of the following relations is true ?

(a)  a + b = c + d

(b)  a – b = c – d

(c)   

(d) a – c = b + d

Answer: (b)

16. is equal to:

(a)  1/2

(b)  1/e

(c)  1

(d) 0

Answer: (c)

17. The total number of positive integral solutions (x, y, z) such that xyz = 24 is

(a)  36

(b)  45

(c)  24

(d) 30

Answer: (d)

18. If a curve passes through the origin and the slope of the tangent to it at any point (x, y) is  then this curve also passes through the point :

(a)  (4, 5)

(b)  (5, 4)

(c)  (4, 4)

(d) (5, 5)

Answer: (d)

19. The value of  where [t] denotes the greatest integer ≤ t, is :

(a)   

(b)   

(c)   

(d)   

Answer: (c)

20. When a missile is fired from a ship, the probability that it is intercepted is 1/3 and the probability that the missile hits the target, given that it is not intercepted, is 3/4. If three missiles are fired independently from the ship, then the probability that all three hit the target, is:

(a)  1/8

(b)  1/27

(c)  3/4

(d) 3/8

Answer: (a)

Section-B

21. Let A1, A2, A3, …. be squares such that for each n ≥ 1, the length of the side of An equals the length of diagonal of An+1. If the length of A1 is 12 cm, then the smallest value of n for which area of An is less than one is ____________.

Answer: (9)

22. The graphs of sine and cosine functions, intersect each other at a number of points and between two consecutive points of intersection, the two graphs enclose the same area A. Then A4 is equal to ___________

Answer: (64)

23. The locus of the point of intersection of the lines (√3)kx + ky – 4√3 = 0 and √3x – y – 4√3 k = 0 is a conic, whose eccentricity is _________.

Answer: (2)

24. If  and  then 13(a2 + b2) is equal to ________.

Answer: (13)

25. Let f(x) be a polynomial of degree 6 in x, in which the coefficient of x6 is unity and it has extrema at x = –1 and x = 1. If  then 5.f(2) is equal to _________.

Answer: (144)

26. The number of points, at which the function f(x) = |2x + 1| − 3|x + 2| + |x2 + x – 2|, x ∈ R is not differentiable, is ________.

Answer: (2)

27. If the system of equations

kx + y + 2z = 1

3x – y – 2z = 2

–2x – 2y – 4z = 3

has infinitely many solutions, then k is equal to __________.

Answer: (21)

28. Let  and  be three given vectors. If  is a vector such that then   is equal to ________

Answer: (12)

29. Let  where x, y and z are real numbers such that x + y + z > 0 and xyz = 2.

If A2 = I3, then the value of x3 + y3 + z3 is ________.

Answer: (7)

30. The total number of numbers, lying between 100 and 1000 that can be formed with the digits 1, 2, 3, 4,5, if the repetition of digits is not allowed and numbers are divisible by either 3 or 5 is ________.

Answer: (32)

JEE Main Session 1 February 24th Shift 2 Question Paper with Answer Key

Physics

Section-A

1. Zener breakdown occurs in a p-n junction having p and n both:

(a)  lightly doped and have wide depletion layer.

(b)  heavily doped and have narrow depletion layer.

(c)  heavily doped and have wide depletion layer.

(d) lightly doped and have narrow depletion layer.

Answer: (b)

2. According to Bohr atom model, in which of the following transitions will the frequency be maximum?

(a)  n = 2 to n = 1

(b)  n = 4 to n = 3

(c)  n = 5 to n = 4

(d) n = 3 to n = 2

Answer: (a)

3. An X-ray tube is operated at 1.24 million volt. The shortest wavelength of the produced photon will be:

(a)  102 nm

(b)  103 nm

(c)  104 nm

(d) 101 nm

Answer: (b)

4. On the basis of kinetic theory of gases, the gas exerts pressure because its molecules:

(a)  suffer change in momentum when impinge on the walls of container.

(b)  continuously stick to the walls of container.

(c)  continuously lose their energy till it reaches wall.

(d) are attracted by the walls of container.

Answer: (a)

5. A circular hole of radius (a/2) is cut out of a circular disc of radius ‘a’ shown in figure. The centroid of the remaining circular portion with respect to point ‘O’ will be:

(a)   

(b)   

(c)   

(d)  

Answer: (d)

6. Given below are two statements:

Statement I: PN junction diodes can be used to function as transistor, simply by connecting two diodes, back to back, which acts as the base terminal.

Statement II: In the study of transistor, the amplification factor β indicates ratio of the collector current to the base current.

In the light of the above statements, choose the correct answer from the options given below.

(a)  Statement I is false but Statement II is true.

(b)  Both Statement I and Statement II are true.

(c)  Statement I is true but Statement II is false.

(d) Both Statement I and Statement II are false.

Answer: (a)

7. When a particle executes SHM, the nature of graphical representation of velocity as a function of displacement is:

(a)  elliptical

(b)  parabolic

(c)  straight line

(d) circular

Answer: (a)

8. Match List – I with List – II.

List-I

(a) Source of microwave frequency

(b) Source of infrared frequency

(c) Source of Gamma Rays

(d) Source of X-rays

List-II

(i) Radioactive decay of nucleus

(ii) Magnetron

(iii) Inner shell electrons

(iv) Vibration of atoms and molecules

(v) LASER

(vi) RC circuit

Choose the correct answer from the options given below:

(a)  (a)-(ii),(b)-(iv),(c)-(i),(d)-(iii)

(b)  (a)-(vi),(b)-(iv),(c)-(i),(d)-(v)

(c)  (a)-(ii),(b)-(iv),(c)-(vi),(d)-(iii)

(d) (a)-(vi),(b)-(v),(c)-(i),(d)-(iv)

Answer: (a)

9. The logic circuit shown below is equivalent to :

Answer: (b)

10. If the source of light used in a Young’s double slit experiment is changed from red to violet:

(a)  the fringes will become brighter.

(b)  consecutive fringe lines will come closer.

(c)  the central bright fringe will become a dark fringe.

(d) the intensity of minima will increase.

Answer: (b)

11. A body weighs 49 N on a spring balance at the north pole. What will be its weight recorded on the same weighing machine, if it is shifted to the equator?

[Use  and radius of earth, R = 6400 km.]

(a)  49 N

(b)  49.83 N

(c)  49.17 N

(d) 48.83 N

Answer: (4)

12. If one mole of an ideal gas at (P1, V1) is allowed to expand reversibly and isothermally (A to B) its pressure is reduced to one-half of the original pressure (see figure). This is followed by a constant volume cooling till its pressure is reduced to one-fourth of the initial value (B→C). Then it is restored to its initial state by a reversible adiabatic compression (C to A). The net work done by the gas is equal to:

(a)  0

(b)   

(c)   

(d) RTln2

Answer: (c)

13. The period of oscillation of a simple pendulum is  Measured value of ‘L’ is 1.0 m from meter-scale having a minimum division of 1 mm and time of one complete oscillation is 1.95 s measured from stopwatch of 0.01 s resolution. The percentage error in the determination of ‘g’ will be:

(a)  1.33%

(b)  1.30%

(c)  1.13%

(d) 1.03%

Answer: (c)

14. In the given figure, a body of mass M is held between two massless springs, on a smooth inclined plane. The free ends of the springs are attached to firm supports. If each spring has spring constant k, the frequency of oscillation of given body is:

(a)   

(b)   

(c)   

(d)  

Answer: (a)

15. Figure shows a circuit that contains four identical resistors with resistance R = 2.0 Ω. Two identical inductors with inductance L = 2.0 mH and an ideal battery with emf E = 9.V. The current ‘i’ just after the switch ‘s’ is closed will be:

(a)  9 A

(b)  3.0 A

(c)  2.25 A

(d) 3.37 A

Answer: (c)

16. The de Broglie wavelength of a proton and α-particle are equal. The ratio of their velocities is:

(a)  4 : 2

(b)  4 : 1

(c)  1 : 4

(d) 4 : 3

Answer: (b)

17. Two electrons each are fixed at a distance ‘2d’. A third charge proton placed at the midpoint is displaced slightly by a distance x (x<<d) perpendicular to the line joining the two fixed charges. Proton will execute simple harmonic motion having angular frequency:

(m = mass o charged particle)

(a)    

(b)    

(c)   

(d)  

Answer: (a)

18. A soft ferromagnetic material is placed in an external magnetic field. The magnetic domains:

(a)  decrease in size and changes orientation.

(b)  may increase or decrease in size and change its orientation.

(c)  increase in size but no change in orientation.

(d) have no relation with external magnetic field.

Answer: (b)

19. Which of the following equations represents a travelling wave?

(a)   

(b)  y = A sin(15x – 2t)

(c)  y = Aex cos (ωt – θ)

(d) y = A sin x cos ωt

Answer: (b)

20. A particle is projected with velocity v0 along x-axis. A damping force is acting on the particle which is proportional to the square of the distance from the origin i.e. ma = −αx2. The distance at which the particle stops:

(a)   

(b)   

(c)    

(d)  

Answer: (*)

Section-B

21. A uniform metallic wire is elongated by 0.04 m when subjected to a linear force F. The elongation, if its length and diameter is doubled and subjected to the same force will be ________ cm.

Answer: (2)

22. A cylindrical wire of radius 0.5 mm and conductivity 5 × 107 S/m is subjected to an electric field of 10 mV/m. The expected value of current in the wire will be x3π mA. The value of x is ____.

Answer: (5)

23. Two cars are approaching each other at an equal speed of 7.2 km/hr. When they see each other, both blow horns having frequency of 676 Hz. The beat frequency heard by each driver will be ________ Hz. [Velocity of sound in air is 340 m/s.]

Answer: (8)

24. A uniform thin bar of mass 6 kg and length 2.4 meter is bent to make an equilateral hexagon. The moment of inertia about an axis passing through the centre of mass and perpendicular to the plane of hexagon is ______×101 kg m2.

Answer: (8)

25. A point charge of +12 μC is at a distance 6 cm vertically above the centre of a square of side 12 cm as shown in figure. The magnitude of the electric flux through the square will be _____ ×103 Nm2/C.

Answer: (226)

26. Two solids A and B of mass 1 kg and 2 kg respectively are moving with equal linear momentum. The ratio of their kinetic energies (K.E.)A : (K.E.)B will be A/1. So the value of A will be ________.

Answer: (2)

27. The root mean square speed of molecules of a given mass of a gas at 270C and 1 atmosphere pressure is 200 ms1. The root mean square speed of molecules of the gas at 127°C and 2 atmosphere pressure is   The value of x will be __________.

Answer: (400 m/s)

28. A series LCR circuit is designed to resonate at an angular frequency ω0 = 105rad/s. The circuit draws 16W power from 120 V source at resonance. The value of resistance ‘R’ in the circuit is _______ Ω.

Answer: (900)

29. An electromagnetic wave of frequency 3 GHz enters a dielectric medium of relative electric permittivity 2.25 from vacuum. The wavelength of this wave in that medium will be _______ ×102

Answer: (667)

30. A signal of 0.1 kW is transmitted in a cable. The attenuation of cable is −5 dB per km and cable length is 20 km. The power received at receiver is 10x The value of x is ______.

Answer: (8)

Chemistry

Section-A

1. The correct order of the following compounds showing increasing tendency towards nucleophilic substitution reaction is:

(a)  (iv) < (i) < (iii) < (ii)

(b)  (iv) < (i) < (ii) < (iii)

(c)  (i) < (ii) < (iii) < (iv)

(d) (iv) < (iii) < (ii) < (i)

Answer: (c)

2. Match List-I with List-II

List-I                                 List-II

(Metal)                              (Ores)

(a) Aluminium                   (i) Siderite

(b) Iron                              (ii) Calamine

(c) Copper                         (iii) Kaolinite

(d) Zinc                             (iv) Malachite

(a)  (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

(b)  (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)

(c)  (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)

(d) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

Answer: (c)

3. Match List-I with List-II

List-I                                 List-II

(Salt)                     (Flame Colour wavelength)

(a) LiCl                  (i) 455.5 m

(b) NaCl                (ii) 970.8 nm

(c) RbCl                (iii) 780.0 nm

(d) CsCl                (iv) 589.2 nm

Choose the correct Answer from the options given below:

(a)  (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

(b)  (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)

(c)  (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)

(d) (a)-(i), (b)-(iv), (c)-(ii), (d)-(iii)

Answer: (b)

4. Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Hydrogen is the most abundant element in the Universe, but it is not the most abundant gas in the troposphere.

Reason R: Hydrogen is the lightest element.

In the light of the above statements, choose the correct Answer from the given below

(1) A is false but R is true

(2) Both A and R are true and R is the correct explanation of A

(3) A is true but R is false

(4) Both A and R are true but R is NOT the correct explanation of A

(a)  A is false but R is true

(b)  Both A and R are true and R is the correct explanation of A

(c)  A is true but R is false

(d) Both A and R are true but R is NOT the correct explanation of A

Answer: (b)

5. Statement-I: The parameter “Biochemical oxygen demand” as an important criteria for survival of aquatic life.

Statement-II : The optimum “Biochemical oxygen demand” is 6.5.

(a)  Both Statement I and Statement II are false

(b)  Statement I is false but Statement II is true

(c)  Statement I is true but Statement II is false

(d) Both Statement I and Statement II are true

Answer: (c)

6. Which one of the following carbonyl compounds cannot be prepared by addition of water on an alkyne in the presence of HgSO4 and H2SO4?

Answer: (a)

7. Which one of the following compounds is non-aromatic?

Answer: (b)

8. The incorrect statement among the following is:

(a)  VOSO4 is a reducing agent

(b)  Red color of ruby is due to the presence of CO3+

(c)  Cr2O3 is an amphoteric oxide

(d) RuO4 is an oxidizing agent

Answer: (b)

9. According to Bohr’s atomic theory:

(A) Kinetic energy of electron is ∝ Z2/n2

(B) The product of velocity (v) of electron and principal quantum number (n). ‘vn’ ∝ z2

(C) Frequency of revolution of electron in an orbit is ∝ Z3/ n3

(D) Coulombic force of attraction on the electron is ∝ Z3/n4

Choose the most appropriate Answer from the options given below

(a)  (C) Only

(b)  (A) and (D) only

(c)  (A) only

(d) (A), (C) and (D) only

Answer: (b)

10. Match List-I with List-I

List-I                                 List-II

(a) Valium                         (iv) Tranquilizer

(b) Morphine                     (iii) Analgesic

(c) Norethindrone             (i) Antifertility drug

(d) Vitamin B12                (ii) Pernicious anemia

(a)  (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

(b)  (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)

(c)  (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)

(d) (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)

Answer: (d)

11. The Correct set from the following in which both pairs are in correct order of melting point is

(a)  LiF > LiCl ; NaCl > MgO

(b)  LiF > LiCl ; MgO > NaCl

(c)  LiCl > LiF ; NaCl > MgO

(d) LiCl > LiF ; MgO > NaCl

Answer: (b)

12. The calculated magnetic moments (spin only value) for species [FeCl4]2, [Co(C2O4)3]3 and MnO42 respectively are:

(a)  5.92, 4.90 and 0 BM

(b)  5.82, 0 and 0 BM

(c)  4.90, 0 and 1.73 BM

(d) 4.90, 0 and 2.83 BM

Answer: (c)

13. Which of the following reagent is suitable for the preparation of the product in the following reaction?

(a)  Red P + Cl2

(b)  NH2NH2/ C2H5ONa+

(c)  Ni/H2

(d) NaBH4

Answer: (b)

14. The diazonium salt of which of the following compounds will form a coloured dye on reaction with β-Naphthol in NaOH?

Answer: (c)

15. What is the correct sequence of reagents used for converting nitrobenzene into m- dibromobenzene?

Answer: (d)

16. The correct shape and I-I-I bond angles respectively in I3 ion are:

(a)  Trigonal planar; 120º

(b)  Distorted trigonal planar; 135º and 90º

(c)  Linear; 180º

(d) T-shaped; 180º and 90º

Answer: (c)

17. What is the correct order of the following elements with respect to their density?

(a)  Cr < Fe < Co < Cu < Zn

(b)  Cr < Zn < Co < Cu < Fe

(c)  Zn < Cu < Co < Fe < Cr

(d) Zn < Cr < Fe < Co < Cu

Answer: (d)

18. Match List-I and List-II.

(a)  (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

(b)  (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)

(c)  (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)

(d) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

Answer: (d)

19. In polymer Buna-S: ‘S’ stands for

(a)  Styrene

(b)  Sulphur

(c)  Strength

(d) Sulphonation

Answer: (a)

20. Most suitable salt which can be used for efficient clotting of blood will be:

(a)  Mg(HCO3)2

(b)  FeSO4

(c)  NaHCO3

(d) FeCl3

Answer: (d)

Section-B

21. The magnitude of the change in oxidising power of the MnO4/Mn2+ couple is x × 10–4 V, if the H+ concentration is decreased from 1M to 10–4 M at 25°C. (Assume concentration of MnO4– and Mn2+ to be same on change in H+ concentration). The value of x is _____. (Rounded off to the nearest integer).

[Given: 230RT/F = 0.059]

Answer: (3776)

22. Among the following allotropic forms of sulphur, the number of allotropic forms, which will show paramagnetism is ______.

(a) α-sulphur (b) β-sulphur (c) S2 form

Answer: (a)

23. C6H6 freezes at 5.5ºC. The temperature at which a solution of 10 g of C4H10 in 200 g of C6H6 freeze is ________ C. (The molal freezing point depression constant of C6H6 is 5.12C/m).

Answer: (1)

24. The volume occupied by 4.75 g of acetylene gas at 50°C and 740 mmHg pressure is _______L. (Rounded off to the nearest integer)

(Given R = 0.0826 L atm K–1 mol–1)

Answer: (5)

25. The solubility product of PbI2 is 8.0 × 10–9. The solubility of lead iodide in 0.1 molar solution of lead nitrate is x × 10–6 mol/L. The value of x is ________ (Rounded off to the nearest integer)

Given √2 = 1.41

Answer: (141)

26. The total number of amines among the following which can be synthesized by Gabriel synthesis is _______

Answer: (3)

27. 1.86 g of aniline completely reacts to form acetanilide. 10% of the product is lost during purification. Amount of acetanilide obtained after purification (in g) is ____× 10–2.

Answer: (243)

28. The formula of a gaseous hydrocarbon which requires 6 times of its own volume of O2 for complete oxidation and produces 4 times its own volume of CO2 is CxHy. The value of y is

Answer: (8)

29. Sucrose hydrolysis in acid solution into glucose and fructose following first order rate law with a half-life of 3.33 h at 25ºC. After 9h, the fraction of sucrose remaining is f. The value of  is _________× 10–2 (Rounded off to the nearest integer)

[Assume: ln10 = 2.303, ln2 = 0.693]

Answer: (81)

30. Assuming ideal behavior, the magnitude of log K for the following reaction at 25ºC is x × 10–1. The value of x is __________. (Integer Answer)

3HC ≡ CH(g) ⇌ C6H6 (l)

[Given: ΔfG° (HC = CH) = –2.04 × 105] mol–1; ΔfG°(C6H6) = – 1.24 × 105 J mol–1;

R = 8.314 J K–1 mol–1]

Answer: (855)

Mathematics

Section-A

1. Let a, b ∈ If the mirror image of the point P(a, 6, 9) with respect to the line  is (20, b, −a, −9), then |a + b| is equal to:

(a)  86

(b)  88

(c)  84

(d) 90

Answer: (b)

2. Let f be a twice differentiable function defined on R such that f(0) = 1, f'(0) = 2 and f'(x) ≠ 0 for all x ∈ If  for all x ∈ R, then the value of f(1) lies in the interval:

(a)  (9, 12)

(b)  (6, 9)

(c)  (3, 6)

(d) (0, 3)

Answer: (b)

3. A possible value of  is :

(a)  1/2√2

(b)  1/√7

(c)  √7 – 1

(d) 2√2 – 1

Answer: (2)

4. The probability that two randomly selected subsets of the set {1, 2, 3, 4, 5} have exactly two elements in their intersection, is:

(a)  65/27

(b)  135/29

(c)  65/28

(d) 35/27

Answer: (b)

5. The vector equation of the plane passing through the intersection of the planes  and the point (1, 0, 2) is:

(a)    

(b)   

(c)   

(d)  

Answer: (b)

6. If P is a point on the parabola y = x2 + 4 which is closest to the straight line y = 4x − 1, then the co-ordinates of P are :

(a)  (–2, 8)

(b)  (1, 5)

(c)  (3, 13)

(d) (2, 8)

Answer: (d)

7. Let a, b, c be in arithmetic progression. Let the centroid of the triangle with vertices (a, c), (2, b) and (a, b) be (10/3, 7/3). If α, β are the roots of the equation ax2 + bx + 1 = 0, then the value of α2 + β2 − αβ is:

(a)  71/256

(b)  −69/256

(c)  6/9/256

(d) −71/256

Answer: (d)

8. The value of the integral,  where [x] denotes the greatest integer less than or equal to x, is:

(a)  −4

(b)  −5

(c)  −√2 – √3 − 1

(d) −√2 – √3 + 1

Answer: (c)

9. Let f : R → R be defined as

Let A = {x ∈ R : f is increasing}. Then A is equal to :

(a)  (−5, −4) ∪ (4,∞)

(b)  (−5, ∞)

(c)  (−∞,−5) ∪ (4, ∞)

(d) (−∞,−5) ∪ (−4, ∞)

Answer: (a)

10. If the curve y = ax2 + bx + c,x ∈ R passes through the point (1, 2) and the tangent line to this curve at origin is y = x, then the possible values of a, b, c are:

(a)  a = 1, b = 1, c = 0

(b)  a = −1, b = 1, c = 1

(c)  a = 1, b = 0, c = 1

(d) a = 1/2, b = 1/2 ,c = 1

Answer: (a)

11. The negation of the statement ~p ∧ (p ∨ q) is∶

(a)  ~ p ∧ q

(b)  p ∧ ~ q

(c)  ~ p ∨ q

(d) p ∨ ∼ q

Answer: (d)

12. For the system of linear equations: x − 2y = 1, x − y + kz = −2, ky + 4z = 6,k ∈ R

Consider the following statements:

(A) The system has unique solution if k ≠ 2,k ≠ −2.

(B) The system has unique solution if k = −2.

(C) The system has unique solution if k = 2.

(D) The system has no-solution if k = 2.

(E) The system has infinite number of solutions if k ≠ −2.

Which of the following statements are correct?

(a)  (B) and (E) only

(b)  (C) and (D) only

(c)  (A) and (D) only

(d) (A) and (E) only

Answer: (c)

13. For which of the following curves, the line x + √3y = 2√3 is the tangent at the point (3√3/2, 1/2)?

(a)  x2 + 9y2 = 9

(b)  2x2 − 18y2 = 9

(c)   

(d) x2 + y2  = 7

Answer: (a)

14. The angle of elevation of a jet plane from a point A on the ground is 600. After a flight of 20 seconds at the speed of 432 km/hour, the angle of elevation changes to 300. If the jet plane is flying at a constant height, then its height is:

(a)  1200√3 m

(b)  1800√3 m

(c)  3600√3 m

(d) 2400√3 m

Answer: (a)

15. For the statements p and q, consider the following compound statements:

(a) (~ q ∧ (p → q)) → ~p

(b) ((p ∨ q)) ∧ ~ p) → q

Then which of the following statements is correct?

(a)  (a) is a tautology but not (b)

(b)  (a) and (b) both are not tautologies

(c)  (a) and (b) both are tautologies

(d) (b) is a tautology but not (a)

Answer: (c)

16. Let A and B be 3 × 3 real matrices such that A is symmetric matrix and B is skew-symmetric matrix. Then the system of linear equations (A2B2 − B2A2)X = O, where X is a 3 × 1 column matrix of unknown variables and O is a 3 × 1 null matrix, has:

(a)  a unique solution

(b)  exactly two solutions

(c)  infinitely many solutions

(d) no solution

Answer: (c)

17. If n ≥ 2 is a positive integer, then the sum of the series n+1C2 + 2(2C2 + 3C2 + 4C2 + …. + nC2) is

(a)    

(b)   

(c)   

(d)  

Answer: (c)

18. If a curve y = f(x) passes through the point (1, 2) and satisfies  then for what value of b,   

(a)  5

(b)  62/5

(c)  31/5

(d) 10

Answer: (4)

19. The area of the region: R{(x, y): 5x2 ≤ y ≤ 2x2 + 9} is:

(a)  9√3 square units

(b)  12√3 square units

(c)  11√3 square units

(d) 6√3 square units

Answer: (b)

20. Let f(x) be a differentiable function defined on [0, 2] such that f’(x) =f'(2 − x) for all x ∈ (0, 2), f(0) = 1 and f(2) = e2. Then the value of  is:

(a)  1 + e2

(b)  1 – e2

(c)  2(1 – e2)

(d) 2(1 + e2)

Answer: (a)

Section-B

21. The number of the real roots of the equation (x + 1)2 + |x – 5| = 27/4 is _______.

Answer: (2)

22. The students S1, S2, … S10 are to be divided into 3 groups A, B, and C such that each group has at least one student and the group C has at most 3 students. Then the total number of possibilities of forming such groups is _____.

Answer: (31650)

23. If a + α = 1, b + β = 2 and  then the value of the expression   is________.

Answer: (2)

24. If the variance of 10 natural numbers 1, 1, 1, …,1, k is less than 10, then the maximum possible value of k is ___________.

Answer: (11)

25. Let λ be an integer. If the shortest distance between the lines x − λ = 2y − 1 = −2z and x = y + 2λ = z − λ is √7/2√2, then the value of |λ| is _________.

Answer: (1)

26. Let  and n = [|k|] be the greatest integral part of |k|. Then  is equal to ________.

Answer: (310)

27. Let a point P be such that its distance from the point (5, 0) is thrice the distance of P from the point (−5, 0). If the locus of the point P is a circle of radius r, then 4r2 is equal to _________.

Answer: (56.25)

28. For integers n and r, let

The maximum value of k for which the sum

exists, is equal to_________.

Answer: (*)

29. The sum of first four terms of a geometric progression (G.P.) is 65/12 and the sum of their respective reciprocals is 65/18. If the product of first three terms of the G.P. is 1, and the third term is α then 2α is________

Answer: (3)

30. If the area of the triangle formed by the positive x-axis, the normal and the tangent to the circle (x − 2)2 + (y − 3)2 = 25 at the point (5, 7) is A, then 24A is equal to ________.

Answer: (*)

JEE Main Session 1 February 24th Shift 1 Question Paper with Answer Key

Physics

Section-A

1. Four identical particles of equal masses 1 kg made to move along the circumference of a circle of radius 1 m under the action of their own mutual gravitational attraction. The speed of each particle will be

(a) 

(b) 

(c) 

(d) 

Answer: (a)

2. Consider two satellites S1 and S2 with periods of revolution 1 hr and 8 hr respectively revolving around a planet in circular orbits. The ratio of angular velocity of satellite S1 to the angular velocity of satellite S2 is

(a)  8 : 1

(b)  1 : 8

(c)  2 : 1

(d) 1 : 4

Answer: (a)

3. n moles of a perfect gas undergoes a cyclic process ABCA (see figure) consisting of the following processes:

A→ B: Isothermal expansion at temperature T so that the volume is doubled from V1 to V2 and pressure changes from P1 to P2.

B → C: Isobaric compression at pressure P2 to initial volume V1.

C → A: Isochoric change leading to change of pressure from P2 to P1.

Total work done in the complete cycle ABCA is –

(a)  0

(b) 

(c)  nRTln2

(d) 

Answer: (d)

4. Two equal capacitors are first connected in series and then in parallel. The ratio of the equivalent capacities in the two cases will be

(a)  2 : 1

(b)  1 : 4

(c)  4 : 1

(d) 1 : 2

Answer: (2)

5. A cell E1 of emf 6V and internal resistance 2Ω is connected with another cell E2 of emf 4V and internal resistance 8Ω (as shown in the figure). The potential difference across points X and Y is

(a)  3.6 V

(b)  10.0V

(c)  5.6V

(d) 2.0V

Answer: (c)

6. If Y, K and η are the values of Young’s modulus, bulk modulus and modulus of rigidity of any material respectively. Choose the correct relation for these parameters.

(a) 

(b) 

(c) 

(d) 

Answer: (a)

7. Two stars of masses m and 2m at a distance d rotate about their common centre of mass in free space. The period of revolution is

(a) 

(b) 

(c) 

(d) 

Answer: (a)

8. If the velocity-time graph has the shape AMB, what would be the shape of the corresponding acceleration-time graph?

Answer: (a)

9. Given below are two statements:

Statement-I: Two photons having equal linear momenta have equal wavelengths.

Statement-II: If the wavelength of a photon is decreased, then the momentum and energy of a photon will also decrease.

In the light of the above statements, choose the correct answer from the options given below.

(a)  Statement-I is false but Statement-II is true

(b)  Both Statement-I and Statement-II are true

(c)  Both Statement-I and Statement-II are false

(d) Statement-I is true but Statement-II is false

Answer: (d)

10. A current through a wire depends on time as i = α0t + βt2 where α0 = 20 A/s and β = 8 As2. Find the charge crossed through a section of the wire in 15 s.

(a)  2100 C

(b)  260 C

(c)  2250 C

(d) 11250 C

Answer: (d)

11. Match List-I with List-II

List-I                                 List-II

(a) Isothermal                    (i) Pressure constant

(b) Isochoric                      (ii) Temperature constant

(c) Adiabatic                     (iii) Volume constant

(d) Isobaric                        (iv) heat content is constant

Choose the correct answer from the options given below:

(a)  (a) – (ii), (b) – (iv), (c) – (iii), (d) – (i)

(b)  (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i)

(c)  (a) – (i), (b) – (iii), (c) – (ii), (d) – (iv)

(d) (a) – (iii), (b) – (ii), (c) – (i), (d) – (iv)

Answer: (b)

12. In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E.

The transition A, B and C respectively represents:

(a)  The series limit of Lyman series, third member of Balmer series and second member of Paschen series

(b)  The first member of the Lyman series, third member of Balmer series and second member of Paschen series

(c)  The ionization potential of hydrogen, second member of Balmer series and third member of Paschen series

(d) The series limit of Lyman series, second member of Balmer series and second member of Paschen series

Answer: (a)

13. The focal length f is related to the radius of curvature r of the spherical convex mirror by:

(a)  f = r

(b) 

(c) 

(d) f = −r

Answer: (c)

14. Moment of inertia (M.I.) of four bodies, having same mass and radius, are reported as:

I1 = M.I. of thin circular ring about its diameter,

I2 = M.I. of circular disc about an axis perpendicular to disc and going through the centre,

I3 = M.I. of solid cylinder about its axis and

I4 = M.I. of solid sphere about its diameter.

(a)  I1 = I2 = I3 < I4

(b) 

(c)  I1 + I3 < I2 + I4

(d) I1 = I2 = I3 > I4

Answer: (d)

15. The work done by a gas molecule in an isolated system is given by,  where x is the displacement, k is the Boltzmann constant and T is the temperature. α and β are constants. Then the dimensions of β will be:

(a)  [M0LT0]

(b)  [M2LT2]

(c)  [MLT2]

(d) [ML2T2]

Answer: (c)

16. If an emitter current is changed by 4mA, the collector current changes by 3.5 mA. The value of β will be:

(a)  7

(b)  0.875

(c)  0.5

(d) 3.5

Answer: (a)

17. In Young’s double-slit experiment, the width of one of the slits is three times the other slit. The amplitude of the light coming from a slit is proportional to the slit-width. Find the ratio of the maximum to the minimum intensity in the interference pattern.

(a)  4 : 1

(b)  2 : 1

(c)  3 : 1

(d) 1 : 4

Answer: (a)

18. In the given figure, a mass M is attached to a horizontal spring which is fixed on one side to a rigid support. The spring constant of the spring is k. The mass oscillates on a frictionless surface with time period T and amplitude A. When the mass is in equilibrium position, as shown in the figure, another mass m is gently fixed upon it. The new amplitude of oscillation will be:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

19. A cube of side ‘a’ has point charges +Q located at each of its vertices except at the origin where the charge is –Q. The electric field at the centre of cube is:

(a) 

(b) 

(c) 

(d) 

Answer: (c)

20. Each side of a box made of metal sheet in cubic shape is ‘a’ at room temperature ‘T’, the coefficient of linear expansion of the metal sheet is ‘α’. The metal sheet is heated uniformly, by a small temperature ΔT, so that its new temperature is T + ΔT. Calculate the increase in the volume of the metal box:

(a) 

(b)  4πa3α∆T

(c)  3πa3α∆T

(d) 4a3α∆T

Answer: (3)

SECTION-B

21. A resonance circuit having inductance and resistance 2 × 10–4 H and 6.28 Ω respectively oscillates at 10 MHz frequency. The value of the quality factor of this resonator is________. [π = 3.14]

Answer: (2000)

22. A ball with a speed of 9 m/s collides with another identical ball at rest. After the collision, the direction of each ball makes an angle of 30° with the original direction. The ratio of velocities of the balls after collision is x : y, where x is _________.

Answer: (1)

23. An audio signal υm = 20sin2π(1500t) amplitude modulates a carrier υc =80 sin 2π (100,000t). The value of percent modulation is ________.

Answer: (25)

24. The coefficient of static friction between a wooden block of mass 0.5 kg and a vertical rough wall is 0.2. The magnitude of horizontal force that should be applied on the block to keep it adhere to the wall will be ______ N. [g = 10 ms2]

Answer: (25)

25. An inclined plane is bent in such a way that the vertical cross-section is given by y = x2/4 where y is in vertical and x in horizontal direction. If the upper surface of this curved plane is rough with a coefficient of friction μ = 0.5, the maximum height in cm at which a stationary block will not slip downward is _____ cm.

Answer: (25)

26. An electromagnetic wave of frequency 5 GHz, is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are 2. Its velocity in this medium is _______ × 107 m/s.

Answer: (15)

27. A hydraulic press can lift 100 kg when a mass ‘m’ is placed on the smaller piston. It can lift _______ kg when the diameter of the larger piston is increased by 4 times and that of the smaller piston is decreased by 4 times keeping the same mass ‘m’ on the smaller piston.

Answer: (25600)

28. A common transistor radio set requires 12 V (D.C.) for its operation. The D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V (A.C.) on standard domestic A.C. supply. The number of turns of the secondary coil are 24, then the number of turns of the primary are ______.

Answer: (440)

29. An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of the light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30° in clockwise direction, the intensity of emerging light will be________ Lumens.

Answer: (75)

30. In connection with the circuit drawn below, the value of current flowing through the 2 kΩ resistor is _______ × 10–4

Answer: (25)

Chemistry

Section-A

1. What is the reason for the formation of a meta product in the following reaction?

(a)  Aniline is ortho/para directing

(b)  Aniline is meta directing

(c)  In acidic medium, aniline is converted into anilinium ion, which is ortho/para directing

(d) In acidic medium, aniline is converted into anilinium ion which is meta directing

Answer: (d)

2. The missing reagent P is:

Answer: (a)

3. Which force is responsible for the stacking of the α-helix structure of protein? Hydrogen (1H, 2H, 3H) is ________

(a)  H-bond

(b)  Ionic bond

(c)  Covalent bond

(d) Van der Waals forces

Answer: (a)

4. The gas evolved due to anaerobic degradation of vegetation causes:

(a)  Global warming and cancer

(b)  Acid rain

(c)  Ozone hole

(d) Metal corrosion

Answer: (a)

5. Match the following:

(i) Caprolactam

(ii) Acrylonitrile

(iii) 2-chlorobuta-1,3-diene

(iv) 2-Methylbuta-1,3-diene

(a) Neoprene

(b) Buna N

(c) Nylon – 6

(d) Natural rubber

(a)  (i) →(b), (ii) → (c), (iii) → (a), (iv) → (d)

(b)  (i) → (a), (ii) → (c), (iii) → (b), (iv) → (d)

(c)  (i) → (c), (ii) → (b), (iii) → (a), (iv) → (d)

(d) (i) → (c), (ii) → (a), (iii) → (b), (iv) → (d)

Answer: (c)

6. What is the major product of the following reaction

Answer: (a)

7. What is the major product of the following reaction?

Answer: (c)

8. Identify the major product:

Answer: (b)

9. The products A and B are:

Answer: (a)

10. Which reagent (A) is used for the following given conversion?

(a)  Cu / ∆ / high pressure

(b)  Molybdenum Oxide

(c)  Manganese Acetate

(d) Potassium Permanganate

Answer: (b)

11. Find A and B.

Answer: (c)

12. Which of the following pairs are isostructural

(A) TiCl4, SiCl4

(B) SO32, CrO32−

(C) NH3, NO3

(D) ClF3, BCl­3

(a)  A, B

(b)  A, C

(c)  B, C

(d) A, D

Answer: (a)

13. Which of the following ores are concentrated by cyanide of group 1st element?

(a)  Sphalerite

(b)  Malachite

(c)  Calamine

(d) Siderite

Answer: (a)

14. S-1: Colourless cupric metaborate is converted into cuprous metaborate in a luminous flame.

S-2: Cuprous metaborate is formed by reacting copper sulphate with boric anhydride heated in non luminous flame.

(a)  S1 is true and S2 is false

(b)  S1 is false and S2 is true

(c)  Both are false

(d) Both are true.

Answer: (c)

15. In the given reactions,

(1) I2 + H2O2 + 2OH → 2I + 2H2O + O2

(2) H2O2 + HOCl → Cl + H3O+ + O2

(a)  H2O2 acts as an oxidising agent in both the reactions

(b)  H2O2 acts as a reducing agent in both the reactions

(c)  H2O2 acts as an oxidising agent in reaction (1) and as a reducing agent in reaction (2)

(d) H2O2 acts as a reducing agent in reaction (1) and as an oxidizing agent in reaction (2)

Answer: (b)

16. has a positive value for which of the following elements of 3d transition series?

(a)  Cu

(b)  Zn

(c)  Cr

(d) Co

Answer: (a)

17. Identify X, Y, Z in the given reaction sequence.

(a)  X = Na[Al(OH)4] ; Y = CO2 ; Z = Al2O3.xH2O

(b)  X = Na[Al(OH)4] ; Y = SO2 ; Z = Al2O3.xH2O

(c)  X = Al(OH)3 ; Y = CO2 ; Z = Al2O3

(d) X = Al(OH)3 ; Y = SO2 ; Z = Al2O3

Answer: (a)

18. The slope of the straight line given in the following diagram for adsorption is:

(a)  1/n (0 to 1)

(b)  1/n (0.1 to 0.5)

(c)  log n

(d) log (1/n)

Answer: (a)

19. The composition of gun metal is:

(a)  Cu, Zn, Sn

(b)  Al, Mg, Mn, Cu

(c)  Cu, Ni, Fe

(d) Cu, Sn, Fe

Answer: (a)

20. Arrange Mg, Al, Si, P and S in the correct order of their ionisation potentials.

Answer: (P > S > Si > Mg > Al)

Section-B

21. Cl2(g) ⇌ 2Cl (g)

For the given reaction at equilibrium, moles of Cl2(g) is equal to the moles of Cl(g) and the equilibrium pressure is 1atm. If Kp of this reaction is x ×10–1, find x.

Answer: (5)

22. S8 + bOH → cS2 + sS2O32 + H2 Find the value of c.

Answer: (4)

23. Calculate the time taken in seconds for 40% completion of a first order reaction, if its rate constant is 3.3× 104 sec1.

Answer: (1518)

24. For a chemical reaction, Keq is 100 at 300K, the value of ΔG° is –xR Joule at 1 atm pressure. Find the value of x. (Use ln 10 = 2.3)

Answer: (1382)

25. Cu2+ + NH3 ⇌ [Cu(NH3)]2+ K1 = 104

Answer: (1.26)

26. 9.45g of CH2ClCOOH is dissolved in 500 mL of H2O solution and the depression in freezing point of the solution is 0.5°C. Find the percentage dissociation.

Answer: (34.4%)

27. What is the coordination number in Body Centered Cubic (BCC) arrangement of identical particles?

Answer: (8)

28. Among the following compounds, how many are amphoteric in nature?

Be(OH)2, BeO, Ba(OH)2, Sr(OH)2

Answer: (2)

29. 5 g of a solute having molar mass of 90 g/mol is dissolved in water to make a 250 mL solution. Calculate the molarity of the

Answer: (0.2)

30. The mass of Li3+ is 8.33 times the mass of a proton. If Li3+ and proton are accelerated through the same potential difference, then the ratio of de Broglie’s wavelength of Li3+ to proton is x ×10–1. Find x

Answer: (2)

Mathematics

Section-A

1. The locus of the mid-point of the line segment joining the focus of the parabola y2 = 4ax to a moving point of the parabola, is another parabola whose directrix is:

(a)  y = 0

(b)  x = 0

(c)  x = a

(d) y = a

Answer: (b)

2. A scientific committee is to formed from 6 Indians and 8 foreigners, which includes at least 2 Indians and double the number of foreigners as Indians. Then the number of ways, the committee can be formed is:

(a)  560

(b)  1050

(c)  1625

(d) 575

Answer: (c)

3. The equation of the plane passing through the point (1,2,–3) and perpendicular to the planes 3x + y – 2z = 5 and 2x – 5y – z = 7, is:

(a)  3x – 10y – 2z + 11 = 0

(b)  6x – 5y – 2z – 2 = 0

(c)  11x + y + 17z + 38 = 0

(d) 6x – 5y + 2z + 10 = 0

Answer: (c)

4. A man is walking on a straight line. The arithmetic mean of the reciprocals of the intercepts of this line on the coordinate axes is 1/4. Three stones A, B and C are placed at the points (1,1), (2,2), and (4,4) respectively. Then which of these stones is/are on the path of the man?

(a)  (2, 2)

(b)  (4, 4)

(c)  (1, 1)

(d) All the above

Answer: (a)

5. The statement among the following that is a tautology is:

(a)  A ∧ (A ∨ B)

(b)  B → [A ∧ (A → B)]

(c)  A  ∨ (A ∧ B)

(d) [A ∧ (A → B)] → B

Answer: ()

6. Let f : ℝ → ℝ be defined as f(x) = 2x – 1 and g : ℝ − {1} → ℝ be defined as 

Then the composition function f(g(x)) is:

(a)  Both none-one and onto

(b)  onto but not one-one

(c)  Neither one-one nor onto

(d) one-one but not onto

Answer: (d)

7. If f:R→ R is a function defined by  where [.] denotes the greatest integer function, then f is:

(a)  discontinuous only at x = 1

(b)  discontinuous at all integral values of x except at x = 1

(c)  continuous only at x = 1

(d) continuous for every real x

Answer: (d)

8. The function 

(a)  increases in [1/2, ∞)

(b)  decreases (−∞, 1/2]

(c)  increases in (−∞, 1/2]

(d) decreases [1/2, ∞)

Answer: (a)

9. The distance of the point (1, 1, 9) from the point of intersection of the line  and the plane x + y + z = 17 is:

(a)  √38

(b)  19√2

(c)  2√19

(d) 38

Answer: (1)

10.  is equal to:

(a)  2/3

(b)  0

(c)  1/15

(d) 3/2

Answer: (1)

11. Two vertical poles are 150 m apart and the height of one is three times that of the other. If from the middle point of the line joining their feet, an observer finds the angles of elevation of their tops to be complementary, then the height of the shorter pole (in meters) is:

(a)  25

(b)  20√3

(c)  30

(d) 25√3

Answer: (d)

12. If the tangent to the curve y = x3 at the point P(t, t3) meets the curve again at Q, then the ordinate of the point which divides PQ internally in the ratio 1:2 is:

(a)  −2t3

(b)  −t3

(c)  0

(d) 2t3

Answer: (a)

13. The area (in sq. units) of the part of the circle x2 + y2 = 36, which is outside the parabola y2 = 9x, is:

(a)  24π + 3√3

(b)  12π + 3√3

(c)  12π − 3√3

(d) 24π − 3√3

Answer: (d)

14. If  where c is a constant o integration, then the ordered pair (a, b) is equal to:

(a)  (1, −3)

(b)  (1, 3)

(c)  (−1, 3)

(d) (3, 1)

Answer: (b)

15. The population P = P(t) at time ‘t’ of a certain species follows the differential equation  If P(0) = 850, then the time at which population becomes zero is:

(a) 

(b)  2loge 18

(c)  loge 9

(d) loge 18

Answer: (b)

16. The value of −15C1 + 2 ∙ 15C2 – 3 ∙ 15C3+ ….−15 ∙ 15C1 + 14C1+ 14C3 + 14C5 + … 14C11 is

(a)  214

(b)  213 – 13

(c)  216 – 1

(d) 213 – 14

Answer: (4)

17. An ordinary dice is rolled for a certain number of times. If the probability of getting an odd number 2 times is equal to the probability of getting an even number 3 times, then the probability of getting an odd number for odd number of times is:

(a)  3/16

(b)  1/2

(c)  5/16

(d) 1/32

Answer: (b)

18. Let p and q be two positive number such that p + q = 2 and p4 + q4 = 272. Then p and q are roots of the equation:

(a)  x2 – 2x + 2 = 0

(b)  x2 – 2x + 8 = 0

(c)  x2 – 2x + 136 = 0

(d) x2 – 2x + 16 = 0

Answer: (d)

19. If  satisfies the equation t2 – 9t + 8 = 0, then the value of  is:

(a)  3/2

(b)  2√3

(c)  1/2

(d) √3

Answer: (3)

20. The system of linear equations

3x – 2y – kz = 10

2x – 4y – 2z = 6

x + 2y – z = 5m

is inconsistent if:

(a)  k = 3, m = 4/5

(b)  k ≠ 3, m ∈ ℝ

(c)  k ≠ 3, m ≠ 4/5

(d) k = 3, m ≠ 4/5

Answer: (4)

Section-B

21. Let  where α ∈ ℝ. Suppose Q = [qij] is a matrix satisfying PQ = kI3 for some non-zero k ∈ ℝ. If q23 = −k/8 and |Q| = k2/2, then a2  + k2 is equal to________

Answer: (17)

22. Let Bi (i = 1,2,3) be three independent events in a sample space. The probability that only B1 occur is α, only B2 occurs is β and only B3 occurs is γ. Let p be the probability that none of the events Bi occurs and these 4 probabilities satisfy the equations (α − 2β)p ⁡= αβ and (β − 3γ)p⁡= 2βγ (All the probabilities are assumed to lie in the interval (0, 1)). Then  is equal to _____

Answer: (6)

23. The minimum value of α for which the equation  has at least one solution in (0, π/2) is_______

Answer: (9)

24. If one of the diameters of the circle x2 + y2 – 2x – 6y + 6 = 0 is a chord of another circle ‘C’ whose center is at (2, 1), then its radius is ________

Answer: (3)

25. is equal to______

Answer: (1)

26. If  (a > 2) and [x] denotes the greatest integer ≤ x, then  is equal to_________

Answer: (3)

27. Let three vectors  be such that  is coplanar with  is perpendicular to and   then the value of  is_______

Answer: (75)

28. Let A = {n ∈ N ∶ n is a 3-digit number}, B = {9k + 2∶ k ∈ N} and C = {9k + l ∶ k ∈ N} for some l(0 < l < 9). If the sum of all the elements of the set A ∩ (B ∪ C) is 274 × 400, then l is equal to ___________

Answer: (5)

29. If the least and the largest real values of α, for which the equation z + α |z − 1| + 2 i⁡ = 0 (z ∈ ℂ and i = √−1) has a solution, are p and q respectively; then 4(p2 + q2) is equal to _________

Answer: (10)

30. Let M be any 3 × 3 matrix with entries from the set {0, 1, 2}. The maximum number of such matrices, for which the sum of diagonal elements of MTM is seven, is __________

Answer: (540)

JEE Main September 6 2020 Shift 2 Question Paper with Answer Key

Physics

1. For a plane electromagnetic wave, the magnetic field at a point x and time t is  The instantaneous electric field E corresponding to B is:

(speed of light c = 3 × 108 ms1)

(1) 

(2) 

(3) 

(4) 

Answer: (4)

2. Particle A of mass m1 moving with velocity  collides with another particle B of mass m2 which is at rest initially. Let be the velocities of particles A and B after collision  respectively. If m1 = 2m2 and after collision  the angle between  is:

(1)  105°

(2)  15°

(3)  −45°

(4)  60°

Answer: (1)

3. When a car is at rest, its driver sees raindrops falling on it vertically. When driving the car with speed v, he sees that raindrops are coming at an angle 60° from the horizontal. On further increasing the speed of the car to (1 + β) v, this angle changes to 45°. The value β is close to:

(1)  0.50

(2)  0.73

(3)  0.37

(4)  0.41

Answer: (2)

4. A charged particle going around in a circle can be considered to be a current loop. A particle of mass m carrying charge q is moving in a plane with speed v under the influence of magnetic field  The magnetic moment of this moving particle:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

5. A double convex lens has power P and same radii of curvature R of both the surfaces. The radius of curvature of a surface of a plano-convex lens made of the same material with power 1.5 P is:

(1)  R/3

(2)  3R/2

(3)  R/2

(4)  2R

Answer: (1)

6. A circuit to verify Ohm’s law uses ammeter and voltmeter in series or parallel connected correctly to the resistor. In the circuit:

(1)  Ammeter is always connected in series and voltmeter in parallel.

(2)  Both, ammeter and voltmeter must be connected in series.

(3)  Both ammeter and voltmeter must be connected in parallel.

(4)  The ammeter is always used in parallel and voltmeter in series.

Answer: (1)

7. A square loop of side 2a and carrying current I is kept in the xz plane with its centre at the origin. A long wire carrying the same current I is placed parallel to the z-axis and passing through the point (0, b, 0), (b >> a). The magnitude of the torque on the loop about z-axis will be:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

8. In a dilute gas at pressure P and temperature T, the mean time between successive collisions of a molecule varies with T as:

(1)  √T

(2)  1/T

(3)  T

(4)  1/√T

Answer: (4)

9. When a particle of mass m is attached to a vertical spring of spring constant k and released, its motion is described by y (t) = y0sin2ωt, where ‘y’ is measured from the lower end of unstretched spring. Then ω is:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

10. The linear mass density of a thin rod AB of length L varies from A to B as  where x is the distance from A. If M is the mass of the rod then its moment of inertia about an axis passing through A and perpendicular to the rod is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

11. A fluid is flowing through a horizontal pipe of varying cross-section, with speed v ms–1 at a point where the pressure is P pascal. At another point where pressure is P/2 Pascal its speed is V ms–1. If the density of the fluid is kg m–3 and the flow is streamlined, then V is equal to:

(1)

(2) 

(3) 

(4) 

Answer: (2)

12. Three rods of identical cross-section and lengths are made of three different materials of thermal conductivity K1, K2 and K3, respectively. They are joined together at their ends to make a long rod (see figure). One end of the long rod is maintained at 100°C and the other at 0°C (see figure). If the joints of the rod are at 70°C and 20°C in steady-state and there is no loss of energy from the surface of the rod, the correct relationship between K1, K2 and K3 are:

(1)  K1 : K2 = 5 : 2, K1 : K3 = 3 : 5

(2)  K1 < K2 < K3

(3)  K1 : K3 = 2 : 3, K2 : K3 = 2 : 5

(4)  K1 > K2 > K3

Answer: (3)

13. Assuming the nitrogen molecule is moving with r.m.s. velocity at 400 K, the de-Broglie wavelength of nitrogen molecule is close to (Given: nitrogen molecule weight: 4.64 × 10–26 kg, Boltzman constant: 1.38 × 10–23 J/K, Planck constant: 6.63 × 10–34s)

(1)  0.44 Å

(2)  0.34 Å

(3)  0.20 Å

(4)  0.24 Å

Answer: (4)

14. Consider the force F on a charge ‘q’ due to a uniformly charged spherical shell of radius R carrying charge Q distributed uniformly over it. Which one of the following statements is true for F, if ‘q’ is placed at distance r from the centre of the shell?

(1) 

(2) 

(3) 

(4) 

Answer: (2)

15. Two identical electric point dipoles have dipole moments  are held on the x-axis at distance ‘a’ from each other. When released, they move along the x-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is ‘m’, their speed when they are infinitely far apart is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

16. Two planets have masses M and 16 M and their radii are a and 2a, respectively. The separation between the centres of the planets is 10a. A body of mass m is fired from the surface of the larger planet towards the smaller planet along the line joining their centres. For the body to be able to reach at the surface of the smaller planet, the minimum firing speed needed is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

17. In the figure shown, the current in the 10 V battery is close to:

(1)  0.21 A from positive to the negative terminal

(2)  0.36 A from negative to the positive terminal

(3)  0.42 A from positive to the negative terminal

(4)  0.71 A from positive to the negative terminal

Answer: (1)

18. A student measuring the diameter of a pencil of circular cross-section with the help of a vernier scale records the following four readings 5.50 mm, 5.55 mm, 5.45 mm, 5.65 mm. The average of these four readings is 5.5375 mm and the standard deviation of the data is 0.07395 mm. The average diameter of the pencil should therefore be recorded as:

(1)  (5.54 ± 0.07) mm

(2)  (5.5375 ± 0.0740) mm

(3)  (5.5375 ± 0.0739) mm

(4)  (5.538 ± 0.074) mm

Answer: (1)

19. Given the masses of various atomic particles mp = 1.0072 u, mn = 1.0087 u, me = 0.000548 u, mv[bar] = 0, md = 2.0141 u, where p ≡ proton, n ≡ neutron, e ≡ electron, v [bar] ≡ antineutrino and d ≡ deuteron. Which of the following processes is allowed by momentum and energy conservation?

(1)  n + n deuterium atom (electron bound to the nucleus)

(2)  e+ + e → γ

(3)  p → n + e+ + v [bar]

(4)  n + p → d + γ

Answer: (4)

20. A particle moving in the xy plane experiences a velocity-dependent force, where vx and vy are the x and y components of its velocity v. If a is the acceleration of the particle, then which of the following statements is true for the particle?

(1)  The kinetic energy of the particle is constant in time.

(2)  quantity v × a is constant in time

(3)  quantity v . a is constant in time

(4)  F arises due to a magnetic field

Answer: (2)

21. A Young’s double-slit experiment is performed using monochromatic light of wavelength λ. The intensity of light at a point on the screen, where the path difference is λ, is K units. The intensity of light at a point where the path difference is λ / 6 is given by nK/12, where n is an integer. The value of n is __________.

Answer: (9)

22. The centre of mass of the solid hemisphere of radius 8 cm is x from the centre of the flat surface. Then the value of x is __________.

Answer: (3)

23. The output characteristics of a transistor is shown in the figure. When VCE is 10V and IC = 4.0 mA, then the value of βac is __________.

Answer: (150)

24. An engine operates by taking a monatomic ideal gas through the cycle shown in the figure. The percentage efficiency of the engine is close to __________.

Answer: (19%)

25. In a series LR circuit, power of 400W is dissipated from a source of 250 V, 50 Hz. The power factor of the circuit is 0.8. In order to bring the power factor to unity, a capacitor of value C is added in series to the L and R. Taking the value of C as (n/3π) μF, then the value of n is __________.

Answer: (400)

Chemistry

1. Match the following :

(1)  (i)-(d),(ii)-(c),(iii)-(e),(iv)-(a)

(2)  (i)-(b),(ii)-(a),(iii)-(c),(iv)-(d)

(3)  (i)-(b),(ii)-(d),(iii)-(e),(iv)-(a)

(4)  (i)-(d),(ii)-(c),(iii)-(b)-(iv)-(e)

Answer: (1)

2. The IUPAC name of the following compound is:

(1)  2-nitro-4-hydroxymethyl-5-amino benzaldehyde

(2)  3-amino-4-hydroxymethyl-5-nitro benzaldehyde

(3)  4-amino-2-formyl-5-hydroxymehtyl nitrobenzene

(4)  5-amino-4-hydroxymethyl-2-nitro benzaldehyde

Answer: (4)

3. For the given cell;

Cu(s)|Cu2+(C1M)||Cu2+(C2M)|Cu(s)

Change in Gibbs energy (ΔG) is negative, if :

(1)  C2 = √2 C1

(2)  C2 = C1/√2

(3)  C1 = 2C2

(4)  C2 = C1

Answer: (1)

4. Reaction of an inorganic sulphite X with dilute H2SO4 generates compound Y. Reaction of Y with NaOH gives X. Further, the reaction of X with Y and water affords compound Z. Y and Z, respectively, are :

(1)  SO2 and NaHSO3

(2)  S and Na2SO3

(3)  SO2 and Na2SO3

(4)  SO3 and NaHSO3

Answer: (1)

5. The value of KC is 64 at 800 K for the reaction N2(g) + 3H2(g) ⇌ 2NH3(g)

The value of KC for the following reaction is:

(1)  1/4

(2)  8

(3)  1/8

(4)  1/64

Answer: (3)

6. The correct match between Item – I (Starting material) and Item – II (reagent) for the preparation of benzaldehyde is :

Answer: (1)

7. For a d4 metal ion in an octahedral field, the correct electronic configuration is :

(1)  e2g t22g when ∆0 < P

(2)  t42g e0g when ∆0 < P

(3)  t32g e1g when ∆0 > P

(4)  e1g t32g when ∆0 < P

Answer: (4)

8. The correct match between Item – I and Item – II is :

Item-I                                Item-II

(a) Natural rubber              (I) 1, 3-butadiene + styrene

(b) Neoprene                     (II) 1, 3-butadiene + acrylonitrile

(c) Buna-N                        (III) Chloroprene

(d) Buna-S                        (IV) Isoprene

(1)  (a) – (III), (b) – (IV), (c) – (I), (d) – (II)

(2)  (a) – (IV), (b) – (III), (c) – (II), (d) – (I)

(3)  (a) – (IV), (b) – (III), (c) – (I), (d) – (II)

(4)  (a) – (III), (b) – (IV), (c) – (II), (d) – (I)

Answer: (2)

9. Which one of the following statement is not true?

(1)  Lactose contains α-glycosidic linkage between C1 of galactose and C4 of glucose.

(2)  Lactose is a reducing sugar and it gives Fehling’s test.

(3)  On acid hydrolysis, lactose gives one molecule of D(+)-glucose and one molecule of D(+)-galactose.

(4)  Lactose(C11H22O11) is a disaccharide and it contains 8 hydroxyl groups.

Answer: (1)

10. The element that can be refined by distillation is :

(1)  tin

(2)  gallium

(3)  zinc

(4)  nickel

Answer: (3)

11. Match the following compounds (Column-I) with their uses (Column-II) :

Column-I                           Column-II

(I) Ca(OH)2                       (A) Casts of statues

(II) NaCl                           (B) White wash

(III)          (C) Antacid

(IV) CaCO­3                      (D) Washing soda preparation

(1)  (I)-(B),(II)-(C),(III)-(D),(IV)-(A)

(2)  (I)-(C),(II)-(D),(III)-(B),(IV)-(A)

(3)  (I)-(B),(II)-(D),(III)-(A),(IV)-(C)

(4)  (I)-(D),(II)-(A),(III)-(C),(IV)-(B)

Answer: (3)

12. Mischmetal is an alloy consisting mainly of :

(1)  lanthanoid and actinoid metals

(2)  lanthanoid metals

(3)  actinoid metals

(4)  actinoid and transition metals

Answer: (2)

13. For a reaction, 4M(s) + n O2(g) → 2 M2 On (s) the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which :

(1)  the free energy change shows a change from negative to positive value.

(2)  the slope changes from positive to zero

(3)  the slope changes from positive to negative.

(4)  the slope changes from negative to positive.

Answer: (1)

14. The increasing order of the boiling points of the major products A,B and C of the following reaction will be :

(1)  A < B < C

(2)  C < A < B

(3)  A < C < B

(4)  B < C < A

Answer: (4)

15. The average molar mass of chlorine is 35.5g mol1. The ratio of 35Cl to 37Cl in naturally occurring chlorine is close to :

(1)  1 : 1

(2)  3 : 1

(3)  2 : 1

(4)  4 : 1

Answer: (2)

16. Which of the following compound can be prepared in good yield by Gabriel phthalimide synthesis?

Answer: (1)

17. The reaction of NO with N2O4 at 250 K gives:

(1)  N2O

(2)  NO2

(3)  N2O5

(4)  N2O3

Answer: (4)

18. A set of solution is prepared using 180 g of water as a solvent and 10g of different nonvolatile solutes A, B and C. The relative lowering of vapour pressure in the presence of these solutes are in the order [Given, molar mass of A = 100 g mol1 ; B = 200g mol1 ; C = 10,000g mol1]

(1)  A > C > B

(2)  B > C > A

(3)  C > B > A

(4)  A > B > C

Answer: (4)

19. Dihydrogen of high purity (> 99.95%) is obtained through :

(1)  the electrolysis of acidified water using Pt electrodes.

(2)  the reaction of Zn with dilute HCl

(3)  the electrolysis of brine solution

(4)  the electrolysis of warm Ba(OH)2

Answer: (4)

20. A crystal is made up of metal iron ‘M1‘ and ‘M2‘ and oxide ions. Oxide ions form a ccp lattice structure. The cation ‘M1‘ occupies 50% of octahedral voids and the cation ‘M2‘ occupies 12.5% of tetrahedral voids of oxide lattice. The oxidation number of ‘M1‘ and ‘M2‘ are, respectively:

(1)  +2, +4

(2)  +3, +1

(3)  +4, +2

(4)  +1, +3

Answer: (1)

21. For Freundlich adsorption isotherm, a plot of log (x/m) (y-axis) and log p (x-axis) gives a straight line. The intercept and slope for the line is 0.4771 and 2, respectively. The mass of gas, adsorbed per gram of adsorbent if the initial pressure is 0.04 atm, is…………….×104 (log 3=0.4771)

Answer: (48)

22. The atomic number of Unnilunium is …………….

Answer: (101)

23. A solution of phenol in chloroform when treated with aqueous NaOH gives compound P as a major product. The mass percentage of carbon in P is ……………. (to the nearest integer)

(Atomic mass : C = 12; H = 1; O = 16)

Answer: (68.85%)

24. The rate of a reaction decreased by 3.555 times when the temperature was changed from 40°C to 30oC. The activation energy (in KJ mol1) of the reaction is……… [Take; R = 8.314 J mol1 K1 In 3.555 = 1.268]

Answer: (100 kJ/mol.)

25. If the solubility product of AB2 is 3.20 × 1011 M3, then the solubility of AB2 in pure water is ……….× 104 mol L1 [Assuming that neither kind of ion reacts with water].

Answer: (2 × 104 mol/lit)

Mathematics

1. If the normal at an end of a latus rectum of an ellipse passes through an extremity of the minor axis, then the eccentricity e of the ellipse satisfies:

(1)  e4 + 2e2 – 1 = 0

(2)  e2 + 2e – 1 = 0

(3)  e4 + e2 – 1 = 0

(4)  e2 + e – 1 =0

Answer: (3)

2. The set of all real values of λ for which the function f(x) = (1− cos2 x) (λ + sin x),  has exactly one maxima and exactly one minima, is:

(1)  (−3/2, 3/2)

(2)  (−1/2, 1/2)

(3)  (−3/2, 3/2)

(4)  (−1/2, 1/2)

Answer: (1)

3. The probabilities of three events A, B and C are given by P(A) = 0.6, P(B) = 0.4 and P(C) = 0.5. If P (A ∪ B) = 0.8, P (A ∩ C) = 0.3, P (A ∩ B ∩ C) = 0.2, P (B ∩ C) = β and P(A ∪ B ∪C) = α , where 0.85 ≤ α ≤ 0.95 , then β lies in the interval:

(1)  [0.36,0.40]

(2)  [0.25,0.35]

(3)  [0.35,0.36]

(4)  [0.20,0.25]

Answer: (2)

4. The common difference of the A.P. b1, b2,….. bm is 2 more than the common difference of A.P. a1, a2, …an. If a40 = −159, a100 = −399 and b100 = a70, then b1 is equal to:

(1)  −17

(2)  81

(3)  127

(4)  −81

Answer: (4)

5. The integral  equals:

(1)  e(4e – 1)

(2)  e(4e + 1)

(3)  4e2 – 1

(4)  e(2e – 1)

Answer: (1)

6. If the tangent to the curve, y = f(x) = xlogex, (x > 0) at a point (c, f(c)) is parallel to the line-segment joining the points (1,0) and (e, e), then c is equal to:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

7. If  is the solution of the differential equation,   then the function p(x) is equal to:

(1)  cosec x

(2)  cot x

(3)  tan x

(4)  sec x

Answer: (2)

8. If α and β are the roots of the equation 2x(2x + 1) = 1, then β is equal to:

(1)  2α(α – 1)

(2)  −2α(α + 1)

(3)  2α2

(4)  2α(α + 1)

Answer: (2)

9. For all twice differentiable functions f: R→ R, with f(0) = f(1) = f´(0) = 0,

(1)  f”(x) = 0, at every point x∈(0,1)

(2)  f”(x) ≠ 0, at every point x∈(0,1)

(3)  f”(x) = 0, for some x∈(0,1)

(4)  f”(0) = 0

Answer: (3)

10. The area (in sq. units) of the region enclosed by the curves y = x2−1 and y = 1−x2 is equal to:

(1)  4/3

(2)  7/2

(3)  16/3

(4)  8/3

Answer: (4)

11. For a suitably chosen real constant a, let a function, f:R−{−a}→R be defined by  Further suppose that for any real number x ≠ −a and f(x) ≠ −a, (fof) (x) = x. Then f(−1/2) is equal to:

(1)  −3

(2)  3

(3)  1/3

(4)  −1/3

Answer: (2)

12. Let  If B = A + A4, then det (B):

(1)  is one

(2)  lies in (1, 2)

(3)  lies in (2, 3)

(4)  is zero

Answer: (2)

13. The centre of the circle passing through the point (0,1) and touching the parabola y = x2 at the point (2, 4) is :

(1)  (3/10, 16/5)

(2)  (6/5, 53/10)

(3)  (−16/5, 53/10)

(4)  (−53/10, 16/5)

Answer: (3)

14. A plane P meets the coordinate axes at A, B and C respectively. The centroid of a triangle ABC is given to be (1, 1, 2). Then the equation of the line through this centroid and perpendicular to the plane P is:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

15. Let f : R→ R be a function defined by f(x) = max {x, x2}. Let S denote the set of all points in R, where f is not differentiable. Then

(1)  {0, 1}

(2)  an empty set

(3)  {1}

(4)  {0}

Answer: (1)

16. The angle of elevation of the summit of a mountain from a point on the ground is 450. After climbing up one km towards the summit at an inclination of 30° from the ground, the angle of elevation of the summit is found to be 60°. Then the height (in km) of the summit from the ground is:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

17. If the constant term in the binomial expansion of  is 405, then |k| equals:

(1)  1

(2)  9

(3)  2

(4)  3

Answer: (4)

18. Let z = x + iy be a non-zero complex number such that z2 = i|z|2, where i = √−1 , then z lies on the

(1)  line, y = x

(2)  real axis

(3)  imaginary axis

(4)  line, y = −x

Answer: (1)

19. Let L denote the line in the xy-plane with x and y intercepts as 3 and 1 respectively. Then the image of the point (−1, −4) in this line is:

(1)  (11/5, 28/5)

(2)  (8/5, 29/5)

(3)  (29/5, 11/5)

(4)  (29/5, 8/5)

Answer: (1)

20. Consider the statement : “For an integer n, if n3 − 1 is even, then n is odd.” The contrapositive statement of this statement is:

(1)  For an integer n, if n is even, then n3−1 is even

(2)  For an integer n, if n is odd, then n3−1 is even

(3)  For an integer n, if n3−1 is not even, then n is not odd.

(4)  For an integer n, if n is even, then n3−1 is odd

Answer: (4)

21. The number of words (with or without meaning) that can be formed from all the letters of the word “LETTER” in which vowels never come together is:

Answer: (120)

22. If  be two non-zero vectors such that  is perpendicular to  then the value of λ is________

Answer: (1)

23. Consider the data on x taking the values 0, 2, 4, 8, …..,2n with frequencies nC0, nC1, nC2nCn, respectively. If the mean of this data is 728/2n, then n is equal to:________

Answer: (6)

24. Suppose that function f : R→R satisfies f(x+y) = f(x) f(y) for all x, y ∈ R and f(1) = 3. If  then n is equal to ………..

Answer: (5)

25. The sum of distinct values of λ for which the system of equations

(λ − 1)x + (3λ + 1)y + 2λz = 0

(λ − 1) x + (4λ − 2)y + (λ + 3)z = 0

2x + (3λ + 1)y + 3(λ − 1)z = 0 has non-zero solutions, is:

Answer: (3)

JEE Main September 6 2020 Shift 1 Question Paper with Answer Key

Physics

1. Four point masses, each of mass m, are fixed at the corners of a square of side l. The square is rotating with angular frequency ω, about an axis passing through one of the corners of the square and parallel to its diagonal, as shown in the figure. The angular momentum of the square about this axis is:

(1)  4ml2ω

(2)  2ml2ω

(3)  3ml2ω

(4)  ml2ω

Answer: (3)

2. A screw gauge has 50 divisions on its circular scale. The circular scale is 4 units ahead of the pitch scale marking, prior to use. Upon one complete rotation of the circular scale, a displacement of 0.5mm is noticed on the pitch scale. The nature of zero error involved and the least count of the screw gauge, are respectively:

(1)  Positive, 0.1 mm

(2)  Positive, 0.1μ m

(3)  Positive, 10 μm

(4)  Negative, 2 μm

Answer: (3)

3. An electron, a doubly ionized helium ion (He++) and a proton are having the same kinetic energy. The relation between their respective de-Broglie wavelengths λe, λHe++ and λp is:

(1)  λe > λp > λHe++

(2)  λe > λHe++ > λp

(3)  λe < λp < λHe++

(4)  λe < λHe++ = λp

Answer: (1)

4. For the given input voltage waveform Vin(t), the output voltage waveform Vo(t), across the capacitor is correctly depicted by:

Answer: (2)

5. Shown in the figure is a hollow ice cream cone (it is open at the top). If its mass is M, the radius of its top, R and height, H, then its moment of inertia about its axis is:

(1)  MR2/2

(2)  MR2/3

(3) 

(4)  MH2/3

Answer: (1)

6. A satellite is in an elliptical orbit around a planet P. It is observed that the velocity of the satellite when it is farthest from the planet is 6 times less than that when it is closest to the planet. The ratio of distances between the satellite and the planet at closest and farthest points is:

(1)  1 : 2

(2)  1 : 3

(3)  1 : 6

(4)  3 : 4

Answer: (3)

7. You are given that mass of 

Mass of 

and Mass off 

When 20 g of  is converted into  by proton capture, the energy liberated, (in kWh), is: [Mass of nucleon = 1 GeV/c2]

(1)  6.82 × 105

(2)  4.5 × 105

(3)  8 × 106

(4)  1.33 × 106

Answer: (4)

8. If the potential energy between two molecules is given by  then at equilibrium, the separation between molecules, and the potential energy are:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

9. A clock has a continuously moving second’s hand of 0.1 m length. The average acceleration of the tip of the hand (in units of ms–2) is of the order of

(1)  10−3

(2)  10−1

(3)  10−2

(4)  10−4

Answer: (1)

10. Identify the correct output signal Y in the given combination of gates (as shown) for the given inputs A and B.

Answer: (*)

11. An electron is moving along +x direction with a velocity of 6 × 106 ms–1. It enters a region of the uniform electric field of 300 V/cm pointing along +y direction. The magnitude and direction of the magnetic field set up in this region such that the electron keeps moving along the x-direction will be

(1)  3 × 10–4 T, along –z direction

(2)  5 × 10–3 T, along –z direction

(3)  5 × 10–3 T, along +z direction

(4)  3 × 10–4 T, along +z direction

Answer: (3)

12. In the figure below, P and Q are two equally intense coherent sources emitting radiation of wavelength 20 m. The separation between P and Q is 5 m and the phase of P is ahead of that of Q by 90°. A, B and C are three distinct points of observation, each equidistant from the midpoint of PQ. The intensities of radiation at A, B, C will be in the ratio:

(1)  4 : 1 : 0

(2)  2 : 1 : 0

(3)  0 : 1 : 2

(4)  0 : 1 : 4

Answer: (2)

13. A point-like object is placed at a distance of 1 m in front of a convex lens of the focal length of 0.5 m. A plane mirror is placed at a distance of 2 m behind the lens. The position and nature of the final image formed by the system are:

(1)  1 m from the mirror, virtual

(2)  2.6 m from the mirror, virtual

(3)  1 m from the mirror, real

(4)  2.6 m from the mirror, real

Answer: (4)

14. An insect is at the bottom of a hemispherical ditch of radius 1 m. It crawls up the ditch but starts slipping after it is at height h from the bottom. If the coefficient of friction between the ground and the insect is 0.75, then h is: (g = 10 ms–2)

(1)  0.45 m

(2)  0.60 m

(3)  0.20 m

(4)  0.80 m

Answer: (3)

15. Molecules of an ideal gas are known to have three translational degrees of freedom and two rotational degrees of freedom. The gas is maintained at a temperature of T. The total internal energy, U of a mole of this gas, and the value of  are given, respectively by:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

16. An object of mass m is suspended at the end of a massless wire of length L and area of cross-section A. Young modulus of the material of the wire is Y. If the mass is pulled down slightly its frequency of oscillation along the vertical direction is:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

17. An AC circuit has R = 100Ω, C = 2μF and L = 80 mH, connected in series. The quality factor of the circuit is:

(1)  20

(2)  2

(3)  0.5

(4)  400

Answer: (2)

18. Charges Q1 and Q2 are at points A and B of a right angle triangle OAB (see figure). The resultant electric field at point O is perpendicular to the hypotenuse, then Q1/Q2 is proportional to:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

19. A sound source S is moving along a straight track with speed v, and is emitting, the sound of frequency vO (see figure). An observer is standing at a finite distance, at the point O, from the track. The time variation of frequency heard by the observer is best represented by (t0 represents the instant when the distance between the source and observer is minimum)

Answer: (4)

20. A particle of charge q and mass m is moving with velocity –vi (v ≠ 0) towards a large screen placed in the Y-Z plane at a distance d. If there is a magnetic field B = B0k, the minimum value of v for which the particle will not hit the screen is:

(1)  qdB0/m

(2)  qdB0/3m

(3)  2qdB0/m

(4)  qdB0/2m

Answer: (1)

21. Two bodies of the same mass are moving with the same speed, but in different directions in a plane. They have a completely inelastic collision and move together thereafter with a final speed which is half of their initial speed. The angle between the initial velocities of the two bodies (in degree) is ________.

Answer: (120)

22. Suppose that intensity of a laser is The rms electric field, in units of V/m associated with this source is close to the nearest integer is __________. (∈0 = 8.86 × 10–12 C2Nm–2; c = 3 × 108 ms–1)

Answer: (194)

23. The density of a solid metal sphere is determined by measuring its mass and its diameter. The maximum error in the density of the sphere is  If the relative errors in measuring the mass and the diameter are 6.0% and 1.5% respectively, the value of x is_______.

Answer: (1050)

24. Initially a gas of diatomic molecules are contained in a cylinder of volume V1 at a pressure P1 and temperature 250 K. Assuming that 25% of the molecules get dissociated causing a change in the number of moles. The pressure of the resulting gas at temperature 2000 K, when contained in a volume 2V1 is given by P2. The ratio P2/P1 is ________.

Answer: (5)

25. A part of a complete circuit is shown in the figure. At some instant, the value of current I is 1A and it is decreasing at a rate of 102 As–1. The value of the potential difference VP – VQ, (in volts) at that instant, is _________.

Answer: (33)

Chemistry

1. The INCORRECT statement is:

(1)  Cast iron is used to manufacture wrought iron.

(2)  Brass is an alloy of copper and nickel.

(3)  German silver is an alloy of zinc, copper and nickel.

(4)  Bronze is an alloy of copper and tin

Answer: (2)

2. The species that has a spin-only magnetic moment of 5.9 BM, is: (Td= tetrahedral)

(1)  [Ni(CN)4]2 (square planar)

(2)  Ni(CO)4(Td)

(3)  [MnBr4]2(Td)

(4)  [NiCl4]2(Td)

Answer: (3)

3. For the reaction 

(1)  Kc = Kp(RT)1/2

(2)  Kc = Kp(RT)1/2

(3)  Kc = Kp(RT)3/2

(4)  Kc = Kp (RT)

Answer: (1)

4. Consider the following reactions:

A is:

Answer: (1)

5. Arrange the following solutions in the decreasing order of pOH:

(A) 0.01 M HCl

(B) 0.01 M NaOH

(C) 0.01 M CH3COONa

(D) 0.01 M NaCl

(1)  (A) > (C) > (D) > (B)

(2)  (B) > (D) > (C) > (A)

(3)  (B) > (C) > (D) > (A)

(4)  (A) > (D) > (C) > (B)

Answer: (4)

6. The variation of equilibrium constant with temperature is given below :

Temperature Equilibrium Constant

T1= 25°C K1= 10

T2= 100°C K2= 100

The value of ∆H°, ∆G° at T1 and ∆G° at T2 (in Kj mol1) respectively, are close to

[use R = 8.314JK1 mol1]

(1)  28.4, −7.14 and −5.71

(2)  0.64, −7.14 and −5.71

(3)  28.4, −5.71 and −14.29

(4)  0.64, −5.71 and −14.29

Answer: (3)

7. Consider the following reactions

A→ P1; B→ P2; C→ P3; D →P4,

The order of the above reactions are a, b, c and d, respectively. The following graph is obtained when log[rate] vs. log[conc.] are plotted.

Among the following the correct sequence for the order of the reactions is:

(1)  c > a > b > d

(2)  d > a > b > c

(3)  d > b > a > c

(4)  a > b > c > d

Answer: (3)

8. The major product obtained from the following reactions is:

Answer: (3)

9. Which of the following compounds shows geometrical isomerism?

(1)  2-methylpent-1-ene

(2)  4-methylpent-2-ene

(3)  2-methylpent-2-ene

(4)  4-methylpent-1-ene

Answer: (2)

10. The lanthanoid that does NOT shows +4 oxidation state is:

(1)  Dy

(2)  Ce

(3)  Tb

(4)  Eu

Answer: (4)

11. The major products of the following reactions are:

Answer: (1)

12. The major product of the following reaction is:

Answer: (2)

13. The increasing order of pKb values of the following compounds is:

(1)  I < II < III < IV

(2)  II < IV < III < I

(3)  I < II < IV < III

(4)  II < I < III < IV

Answer: (3)

14. kraft temperature is the temperature :

(1)  Above which the aqueous solution of detergents starts boiling

(2)  Below which the formation of micelles takes place.

(3)  Above which the formation of micelles takes place.

(4)  Below which the aqueous solution of detergents starts freezing.

Answer: (3)

15. The set that contains atomic numbers of only transition elements, is?

(1)  9, 17, 34, 38

(2)  21, 25, 42, 72

(3)  37, 42, 50, 64

(4)  21, 32, 53, 64

Answer: (2)

16. Consider the Assertion and Reason given below.

Assertion (A): Ethene polymerized in the presence of Ziegler Natta Catalyst at high temperature and pressure is used to make buckets and dustbins.

Reason (R): High density polymers are closely packed and are chemically inert. Choose the correct answer from the following:

(1)  (A) and (R) both are wrong.

(2)  Both (A) and (R) are correct and (R) is the correct explanation of (A)

(3)  (A) is correct but (R) is wrong

(4)  Both (A) and (R) are correct but (R) is not the correct explanation of (A)

Answer: (2)

17. A solution of two components containing n1 moles of the 1st component and n2 moles of the 2nd component is prepared. M1 and M2 are the molecular weights of component 1 and 2 respectively. If d is the density of the solution in g mL1, C2 is the molarity and x2 is the mole fraction of the 2nd component, then C2 can be expressed as:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

18. The correct statement with respect to dinitrogen is?

(1)  Liquid dinitrogen is not used in cryosurgery.

(2)  N2 is paramagnetic in nature

(3)  It can combine with dioxygen at 25°C

(4)  It can be used as an inert diluent for reactive chemicals.

Answer: (4)

19. Among the sulphates of alkaline earth metals, the solubility of BeSO4 and MgSO4 in water, respectively, are:

(1)  Poor and High

(2)  High and high

(3)  Poor and poor

(4)  High and poor

Answer: (2)

20. The presence of soluble fluoride ion upto 1ppm concentration in drinking water, is:

(1)  Harmful to skin

(2)  Harmful to bones

(3)  Safe for teeth

(4)  Harmful for teeth

Answer: (3)

21. A spherical balloon of radius 3cm containing helium gas has a pressure of 48 × 103 At the same temperature, the pressure, of a spherical balloon of radius 12 cm containing the same amount of gas will be…………………….× 106 bar.

Answer: (750)

22. The elevation of boiling point of 0.10m aqueous CrCl3 xNH3 solution is two times that of 0.05 m aqueous CaCl2 The value of x is……………..

[Assume 100% ionisation of the complex and CaCl2, coordination number of Cr as 6, and that all NH3 molecules are present inside the coordination sphere]

Answer: (5)

23. Potassium chlorate is prepared by the electrolysis of KCl in basic solution

If only 60% of the current is utilized in the reaction, the time (rounded to the nearesthour) required to produce 10g of KClO3 using a current of 2A is ………….

(Given: F = 96,500 C mol1; molar mass of KClO3=122 g mol1)

Answer: (11)

24. In an estimation of bromine by Carius method, 1.6 g of an organic compound gave 1.88 g of AgBr. The mass percentage of bromine in the compound is……. .(Atomic mass, Ag=108, Br=80 g mol–1)

Answer: (50%)

25. The number of Cl = O bonds in perchloric acid is, “……………”

Answer: (3)

Mathematics

1. The region represented by {z = x + iy ∈ C : z − Re(z) ≤ 1} is also given by the inequality: {z = x + iy ∈ C : z − Re(z) ≤ 1}

(1) 

(2) 

(3)  y2 ≥ 2 (x + 1)

(4)  y2 ≥ x + 1

Answer: (1)

2. The negation of the Boolean expression p (~p ∧ q) is equivalent to:

(1)  p∧~q

(2)  ~p~q

(3)  ~pq

(4)  ~p∧~q

Answer: (4)

3. The general solution of the differential equation  is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

4. Let L1 be a tangent to the parabola y2 = 4(x+1) and L2 be a tangent to the parabola y2 = 8(x+2) such that L1 and L2 intersect at right angles. Then L1 and L2 meet on the straight line:

(1)  x + 2y =0

(2)  x + 2 = 0

(3)  2x + 1 = 0

(4)  x + 3 = 0

Answer: (4)

5. The area (in sq. units) of the region A = {(x, y): |x| + |y| ≤ 1, 2y2|x|}

(1)  1/6

(2)  5/6

(3)  1/3

(4)  7/6

Answer: (2)

6. The shortest distance between the lines  and x + y + z + 1 = 0, 2x – y + z + 3 = 0 is:

(1)  1

(2)  1/√2

(3)  1/√3

(4)  1/2

Answer: (3)

7. Let a, b, c, d and p be any non zero distinct real numbers such that (a2 + b2 + c2) p2 − 2(ab + bc + cd) p + (b2 + c2 + d2) = 0. Then:

(1)  a, c, p are in G.P.

(2)  a, b, c, d are in G.P.

(3)  a, b, c, d are in A.P.

(4)  a, c, p are in A.P.

Answer: (2)

8. Two families with three members each and one family with four members are to be seated in a row. In how many ways can they be seated so that the same family members are not separated?

(1)  2! 3! 4!

(2)  (3!)3(4!)

(3)  3!(4!)3

(4)  (3!)2(4!)

Answer: (2)

9. The values of λ and μ for which the system of linear equations

x + y + z = 2

x + 2y + 3z = 5

x + 3y + λz = μ

has infinitely many solutions are, respectively:

(1)  6 and 8

(2)  5 and 8

(3)  5 and 7

(4)  4 and 9

Answer: (2)

10. Let m and M be respectively the minimum and maximum values of 

Then the ordered pair (m, M) is equal to:

(1)  (−3, −1)

(2)  (−4, −1)

(3)  (1, 3)

(4)  (−3, 3)

Answer: (1)

11. A ray of light coming from the point (2, 2√3) is incident at an angle 30° on the line x = 1 at the point A. The ray gets reflected on the line x = 1 and meets x-axis at the point B. Then, the line AB passes through the point:

(1)  (4, −√3)

(2)  (3, −1/√3)

(3)  (3, −√3)

(4)  (4, −√3/2)

Answer: (3)

12. Out of 11 consecutive natural numbers if three numbers are selected at random (without repetition), then the probability that they are in A.P. with positive common difference, is:

(1)  10/99

(2)  5/33

(3)  15/101

(4)  5/101

Answer: (2)

13. If f(x + y) = f(x) f(y) and  where N is the set of all natural number, then the value of   is:

(1)  2/3

(2)  1/9

(3)  1/3

(4)  4/9

Answer: (4)

14. If {p} denotes the fractional part of the number p, then  is equal to:

(1)  5/8

(2)  1/8

(3)  7/8

(4)  3/8

Answer: (2)

15. Which of the following points lies on the locus of the foot of perpendicular drawn upon any tangent to the ellipse  from any of its foci?

(1)  (−1, √3)

(2)  (−2, √3)

(3)  (−1, √2)

(4)  (1, 2)

Answer: (1)

16. 

(1)  is equal to 1

(2)  is equal to 1/2

(3)  does not exist

(4)  is equal to −1/2

Answer: (*)

17. If  (n, a > 1) then the standard deviation of n observations x1, x2, x3…xn is:

(1) 

(2) 

(3)  a – 1

(4) 

Answer: (4)

18. If α and β be two roots of the equation x2 − 64x + 256 = 0. Then the value of  is :

(1)  1

(2)  3

(3)  2

(4)  4

Answer: (3)

19. The position of a moving car at time t is given by f(t) = at2 + bt + c, t > 0, where a, b and c are real numbers greater than 1. Then the average speed of the car over the time interval [t1, t2] is attained at the point :

(1)  (t1 + t2)/2

(2)  2a(t1 + t2) + b

(3)  (t2 – t1)/2

(4)  a(t2 – t1) + b

Answer: (1)

20. If  and  such that I2 = αI1 then α equals to:

(1)  5050/5049

(2)  5050/5051

(3)  5051/5050

(4)  5049/5050

Answer: (2)

21. If  are unit vectors, then the greatest value of  is ______.

Answer: (4)

22. Let AD and BC be two vertical poles at A and B respectively on a horizontal ground. If AD = 8 m, BC = 11 m and AB = 10 m; then the distance (in meters) of a point M on AB from the point A such that MD2 + MC2 is minimum is:

Answer: (5)

23. Let f : R → R be defined as

The value of λ for which f´´(0) exists, is _______.

Answer: (5)

24. The angle of elevation of the top of a hill from a point on the horizontal plane passing through the foot of the hill is found to be 45°. After walking a distance of 80 meters towards the top, up a slope inclined at an angle of 30° to the horizontal plane, the angle of elevation of the top of the hill becomes 75°. Then the height of the hill (in meters) is:

Answer: (80)

25. Set A has m elements and set B has n elements. If the total number of subsets of A is 112 more than the total number of subsets of B, then the value of m∙n is

Answer: (28)

JEE Main September 5 2020 Shift 2 Question Paper with Answer Key

Physics

1. A ring is hung on a nail. It can oscillate, without slipping or sliding

(i) in its plane with a time period T1 and,

(ii) back and forth in a direction perpendicular to its plane, with a period T2.

The ratio T1/T2 will be:

(1)  3/√2

(2)  √2/3

(3)  2/√3

(4)  2/3

Answer: (3)

2. The correct match between the entries in column I and column II are:

I II
Radiation Wavelength
(a) Microwave (i) 100 m
(b) Gamma rays (ii) 10–15 m
(c) A.M. radio waves (iii) 10–10 m
(d) X-rays (iv) 10–3 m

(1)  (a) – (ii), (b)-(i), (c)-(iv), (d)-(iii)

(2)  (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)

(3)  (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)

(4)  (a)-(i),(b)-(iii), (c)-(iv), (d)-(ii)

Answer: (3)

3. In an experiment to verify Stokes law, a small spherical ball of radius r and density falls under gravity through a distance h in the air before entering a tank of water. If the terminal velocity of the ball inside water is the same as its velocity just before entering the water surface, then the value of h is proportional to (ignore viscosity of air)

(1)  r4

(2)  r

(3)  r3

(4)  r2

Answer: (1)

4. Ten charges are placed on the circumference of a circle of radius R with constant angular separation between successive charges. Alternate charges 1, 3, 5, 7, 9 have charge (+q) each, while 2, 4, 6, 8, 10 have charge (–q) each. The potential V and the electric field E at the centre of the circle are respectively: (Take V= 0 at infinity)

(1)  V = 0; E = 0

(2)   

(3)   

(4)   

Answer: (1)

5. A spaceship in space sweeps stationary interplanetary dust. As a result, its mass increases at a rate  where v(t) is its instantaneous velocity. The instantaneous acceleration of the satellite is:

(1)  −bv3(t)

(2) 

(3)   

(4)   

Answer: (2)

6. Two different wires having lengths L1 and L2, and respective temperature coefficient of linear expansion α1 and α2, are joined end-to-end. Then the effective temperature coefficient of linear expansion is:

(1)    

(2) 

(3)   

(4)   

Answer: (1)

7. In the circuit, given in the figure currents in different branches and the value of one resistor are shown. Then potential at point B with respect to the point A is:

(1)  +2 V

(2)  −2 V

(3)  +1 V

(4)  −1 V

Answer: (3)

8. The velocity (v) and time (t) graph of a body in a straight line motion is shown in the figure. The point S is at 4.333 seconds. The total distance covered by the body in 6 s is:

(1)  37/3 m

(2)  49/4 m

(3)  12 m

(4)  11 m

Answer: (1)

9. An infinitely long straight wire carrying current I, one side opened rectangular loop and a conductor C with a sliding connector are located in the same plane, as shown in the figure. The connector has length l and resistance R. It slides to the right with a velocity v. The resistance of the conductor and the self-inductance of the loop are negligible. The induced current in the loop, as a function of separation r, between the connector and the straight wire is:

(1)   

(2)   

(3)  

(4)   

Answer: (1)

10. Two Zener diodes (A and B) having breakdown voltages of 6 V and 4 V respectively, are connected as shown in the circuit below. The output voltage VO variation with input voltage linearly increasing with time is given by (Vinput = 0 V at t = 0) (figures are qualitative)

Answer: (4)

11. In an adiabatic process, the density of a diatomic gas becomes 32 times its initial value. The final pressure of the gas is found to be n times the initial pressure. The value of n is:

(1)  32

(2)  1/32

(3)  326

(4)  128

Answer: (4)

12. A galvanometer is used in the laboratory for detecting the null point in electrical experiments. If on passing a current of 6 mA it produces a deflection of 2°, its figure of merit is close to:

(1)  6 × 10–3 A/div.

(2)  3 × 10–3 A/div.

(3)  666° A/div.

(4)  333° A/div.

Answer: (2)

13. In the circuit shown, charge on the 5μF capacitor is:

(1)  5.45 μc

(2)  18.00 μc

(3)  10.90 μc

(4)  16.36 μc

Answer: (4)

14. A parallel plate capacitor has a plate of length ‘l’, width ‘w’ and separation of plates is ‘d’. It is connected to a battery of emf V. A dielectric slab of the same thickness ‘d’ and of dielectric constant k = 4 is being inserted between the plates of the capacitor. At what length of the slab inside plates, will the energy stored in the capacitor be two times the initial energy stored?

(1)  2I/3

(2)  I/2

(3)  I/4

(4)  I/3

Answer: (4)

15. A radioactive nucleus decays by two different processes. The half-life for the first process is 10 s and that for the second is 100 s. The effective half-life of the nucleus is close to:

(1)  55 sec.

(2)  6 sec.

(3)  12 sec.

(4)  9 sec.

Answer: (4)

16. A driver in a car, approaching a vertical wall, notices that the frequency of his car horn has changed from 440 Hz to 480 Hz when it gets reflected from the wall. If the speed of sound in air is 345 m/s, then the speed of the car is:

(1)  24 km/hr

(2)  36 km/hr

(3)  54 km/hr

(4)  18 km/hr

Answer: (3)

17. An iron rod of volume 10–3m3 and relative permeability 1000 is placed as core in a solenoid with 10 turns/cm. If a current of 0.5 A is passed through the solenoid, then the magnetic moment of the rod will be:

(1)  0.5 × 102 Am2

(2)  50 × 102 Am2

(3)  5 × 102 Am2

(4)  500 × 102 Am2

Answer: (3)

18. Two coherent sources of sound, S1 and S2, produce sound waves of the same wavelength, λ = 1 m, in phase. S1 and S2 are placed 1.5 m apart (see fig). A listener, located at L, directly in front of S2 finds that the intensity is at a minimum when he is 2 m away from S2. The listener moves away from S1, keeping his distance from S2 The adjacent maximum of intensity is observed when the listener is at a distance d from S1. Then, d is :

(1)  12 m

(2)  2 m

(3)  3 m

(4)  5 m

Answer: (3)

19. The quantities  are defined where C – capacitance, R – Resistance, L – length, E – Electric field, B – magnetic field and ε0, μ0 – free space permittivity and permeability respectively. Then:

(1)  Only y and z have the same dimension

(2)  x, y and z have the same dimension

(3)  Only x and y have the same dimension

(4)  Only x and z have the same dimension

Answer: (2)

20. The acceleration due to gravity on the earth’s surface at the poles is g and angular velocity of the earth about the axis passing through the pole is ω. An object is weighed at the equator and at a height h above the poles by using a spring balance. If the weights are found to be same, then h is : (h < < R, where R is the radius of the earth)

(1)  R2ω2/g

(2)  R2ω2/8g

(3)  R2ω2/4g

(4)  R2ω2/2g

Answer: (4)

21. Nitrogen gas is at 300° C temperature. The temperature (in K) at which the rms speed of a H2 molecule would be equal to the rms speed of a nitrogen molecule, is _________. (Molar mass of N2 gas 28 g).

Answer: (41)

22. The surface of a metal is illuminated alternately with photons of energies E1 = 4 eV and E2 = 2.5 eV respectively. The ratio of maximum speeds of the photoelectrons emitted in the two cases is 2. The work function of the metal in (eV) is _________.

Answer: (2)

23. A prism of angle A = 1° has a refractive index μ = 1.5. A good estimate for the minimum angle of deviation (in degrees) is close to N/10. Value of N is

Answer: (5)

24. A body of mass 2 kg is driven by an engine delivering a constant power of 1 J/s. The body starts from rest and moves in a straight line. After 9 seconds, the body has moved a distance (in m) _____________.

Answer: (18)

25. A thin rod of mass 0.9 kg and length 1 m is suspended, at rest, from one end so that it can freely oscillate in the vertical plane. A particle of mass 0.1 kg moving in a straight line with velocity 80 m/s hits the rod at its bottom most point and sticks to it (see figure). The angular speed (in rad/s) of the rod immediately after the collision will be __________.

Answer: (20)

Chemistry

1. The major product formed in the following reaction is:

(1)  CH3CH(Br)CH2CH(CH3)2

(2)  CH3CH2CH2C(Br)(CH3)2

(3)  CH3CH2CH(Br)CH(CH3)2

(4)  Br(CH2)3CH(CH3)2

Answer: (1)

2. Hydrogen peroxide, in the pure state, is:

(1)  Linear and blue in color

(2)  Linear and almost colorless

(3)  Non-planar and almost colorless

(4)  Planar and blue in color

Answer: (3)

3. Boron and silicon of very high purity can be obtained through:

(1)  Liquation

(2)  Electrolytic refining

(3)  Zone refining

(4)  Vapour phase refining

Answer: (3)

4. The following molecule acts as an:

(1)  Anti-histamine

(2)  Antiseptic

(3)  Anti-depressant

(4)  Anti-bacterial

Answer: (1)

5. Among the following compounds, geometrical isomerism is exhibited by:

Answer: (1 and 2)

6. Adsorption of a gas follows Freundlich adsorption isotherm. If x is the mass of the gas adsorbed on mass m of the adsorbent, the correct plot of x/m versus p is:

Answer: (2)

7. The compound that has the largest H–M–H bond angle (M=N, O, S, C) is:

(1)  CH4

(2)  H2S

(3)  NH3

(4)  H2O

Answer: (1)

8. The correct statement about probability density (except at infinite distance from nucleus) is :

(1)  It can be zero for 3p orbital

(2)  It can be zero for 1s orbital

(3)  It can never be zero for 2s orbital

(4)  It can negative for 2p orbital

Answer: (1)

9. The rate constant (k) of a reaction is measured at different temperatures (T), and the data are plotted in the given figure. The activation energy of the reaction in kJ mol–1 is: (R is gas constant)

(1)  R

(2)  2/R

(3)  1/R

(4)  2R

Answer: (4)

10. The variation of molar conductivity with concentration of an electrolyte (X) in aqueous solution is shown in the given figure.

The electrolyte X is:

(1)  HCl

(2)  CH + COOH

(3)  NaCl

(4)  KNO3

Answer: (2)

11. The final major product of the following reaction is:

Answer: (3)

12. The major product of the following reaction is :

Answer: (3)

13. Lattice enthalpy and enthalpy of solution of NaCl are 788 kJ mol–1, and 4 kJ mol–1, respectively. The hydration enthalpy of NaCl is:

(1)  −780kJ mol1

(2)  784 kJ mol1

(3)  −784kJ mol1

(4)  780 kJ mol1

Answer: (3)

14. Reaction of ammonia with excess Cl2 gives:

(1)  NH4Cl and N2

(2)  NH4Cl and HCl

(3)  NCl3 and HCl

(4)  NCl3 and NH4Cl

Answer: (3)

15. Which one of the following polymers is not obtained by condensation polymerisation?

(1)  Bakelite

(2)  Nylon 6

(3)  Buna-N

(4)  Nylon 6, 6

Answer: (3)

16. Consider the comples ions, trans-[Co(en)2Cl2]+ (A) and cis-[Co(en)2Cl2]+ (B). The correct statement regarding them is:

(1)  Both (A) and (B) can be optically active.

(2)  (A) can be optically active, but (B) cannot be optically active.

(3)  Both (A) and (B) cannot be optically active.

(4)  (A) cannot be optically active, but (B) can be optically active.

Answer: (4)

17. An element crystallises in a face-centred cubic (fcc) unit cell with cell edge a. The distance between the centres of two nearest octahedral voids in the crystal lattice is:

(1)  a

(2)  a/2

(3)  √2a

(4)  a/√2

Answer: (4)

18. The correct order of the ionic radii of O2–, N3–, F, Mg2+, Na+ and Al3+ is:

(1)  N3– < O2– < F < Na+ < Mg2+ < Al3+

(2)  N3– < F < O2– < Mg2+ < Na+ < Al3+

(3)  Al3+ < Na+ < Mg2+ < O2– < F < N3–

(4)  Al3+ < Mg2+ < Na+ < F < O2– < N3–

Answer: (4)

19. The increasing order of boiling points of the following compounds is:

(1)  I < III < IV < II

(2)  IV < I < II < III

(3)  I < IV < III < II

(4)  III < I < II < IV

Answer: (3)

20. The one that is NOT suitable for the removal of permanent hardness of water is:

(1)  Ion-exchange method

(2)  Calgon’s method

(3)  Treatment with sodium carbonate

(4)  Clark’s method

Answer: (4)

21. For a reaction X + Y ⇌ 2Z, 1.0 mol of X, 1.5 mol of Y and 0.5 mol of Z were taken in a 1 L vessel and allowed to react. At equilibrium, the concentration of Z was 1.0 mol L–1. The equilibrium constant of reaction is ________ x/15. The value of x is _________.

Answer: (16)

22. The volume, in mL, of 0.02 M K2Cr2O7 solution required to react with 0.288 g of ferrous oxalate in acidic medium is ________. (Molar mass of Fe= 56 g mol–1)

Answer: (50 ml)

23. Considering that ∆0 > P, the magnetic moment (in BM) of [Ru(H2O)6]2+ would be ________.

Answer: (0)

24. For a demerization reaction, 2A(g) → A2(g) at 298 K, ∆U = −20 kJ mol1, ∆S = −30 kJ mol1, then the ∆G will be__________ J

Answer: (13538 J)

25. The number of chiral carbons present in sucrose is ______.

Answer: (9)

Mathematics

1. If x = 1 is a critical point of the function f(x) = (3x2 + ax – 2 – a)ex, then:

(1)  x = 1 is a local minima and x = −2/3 is a local maxima of f.

(2)  x = 1 is a local maxima and x = −2/3 is a local minima of f.

(3)  x = 1 and x = −2/3 are local minima of f.

(4)  x = 1 and x = −2/3 are local maxima of f.

Answer: (1)

2.

(1)  is equal to √e

(2)  is equal to 1

(3)  is equal to 0

(4)  does not exist

Answer: (2)

3. The statement (p → (q → p)) → (p → (p ˅ q)) is:

(1)  equivalent to (p˅q)˄ (~ p)

(2)  equivalent to (p˄q)˅(~ p)

(3)  a contradiction

(4)  a tautology

Answer: (4)

4. If  and  then:

(1)    

(2)   

(3)   

(4)    

Answer: (1)

5. If the sum of the first 20 terms of the series  is 460, then x is equal to:

(1)  71/2

(2)  72

(3)  e2

(4)  746/21

Answer: (2)

6. There are 3 sections in a question paper and each section contains 5 questions. A candidate has to answer a total of 5 questions, choosing at least one question from each section. Then the number of ways, in which the candidate can choose the questions, is:

(1)  2250

(2)  2255

(3)  1500

(4)  3000

Answer: (1)

7. If the mean and the standard deviation of the data 3,5,7,a,b are 5 and 2 respectively, then a and b are the roots of the equation:

(1)  x2 – 20x + 18 = 0

(2)  x2 – 10x + 19 = 0

(3)  2x2 – 20x + 19 = 0

(4)  x2 – 10x + 18 = 0

Answer: (2)

8. The derivative of  with respect to  is:

(1)  2√3/3

(2)  2√3/5

(3)  √3/12

(4)  √3/10

Answer: (4)

9. If  where C is a constant of integration, then  can be:

(1)    

(2)   

(3)   

(4)   

Answer: (1)

10. If the length of the chord of the circle, x2 + y2 = r2 (r > 0) along the line, y-2x = 3 is r, then r2 is equal to:

(1)  12

(2)  24/5

(3)  9/5

(4)  12/5

Answer: (4)

11. If α and β are the roots of the equation, 7x2 – 3x – 2 = 0, then the value of  is equal to:

(1)  27/32

(2)  1/24

(3)  27/16

(4)  3/8

Answer: (3)

12. If the sum of the second, third and fourth terms of a positive term G.P. is 3 and the sum of its sixth, seventh and eighth terms is 243, then the sum of the first 50 terms of this G.P. is:

(1)    

(2)    

(3)   

(4)   

Answer: (4)

13. If the line y = mx + c is a common tangent to the hyperbola  and the circle x2 + y2 = 36, then which one of the following is true?

(1)  4c2 = 369

(2)  c2 = 369

(3)  8m + 5 = 0

(4)  5m = 4

Answer: (1)

14. The area (in sq. units) of the region A = {(x,y): (x – 1) [x] ≤ y ≤ 2√x, 0 ≤ x ≤ 2} where [t] denotes the greatest integer function, is:

(1)   

(2)    

(3)   

(4)   

Answer: (2)

15. If a + x = b + y = c + z + 1, where a, b, c, x, y, z are non-zero distinct real numbers, then  is equal to:

(1)  y(a – b)

(2)  0

(3)  y(b – a)

(4)  y(a – c)

Answer: (1)

16. If for some α ∈ R, the lines  and  coplanar, then the line L2 passes through the point:

(1)  (2, −10, −2)

(2)  (10, −2, −2)

(3)  (10, 2, 2)

(4)  (−2, 10, 2)

Answer: (1)

17. The value of  is:

(1)  215i

(2)  −215

(3)  −215i

(4)  65

Answer: (3)

18. Let y = y(x) be the solution of the differential equation  If y(π/3) = 0, then y(π/4) is equal to:

(1)  2 + √2

(2)  √2 – 2

(3) 

(4)  2 – √2

Answer: (2)

19. If the system of linear equations

x + y + 3z = 0

x + 3y + k2z = 0

3x + y + 3z = 0

has a non-zero solution (x, y, z) for some k ∈ R, then  is equal to:

(1)  −9

(2)  9

(3)  −3

(4)  3

Answer: (3)

20. Which of the following points lies on the tangent to the curve  at the point (1, 0) ?

(1)  (2, 6)

(2)  (2, 2)

(3)  (−2, 6)

(4)  (−2, 4)

Answer: (3)

21. Let A = {a, b, c} and B = {1, 2, 3, 4}. Then the number of elements in the set C = {f : A → B 2 ∈ f(A)and f is not one-one} is_______

Answer: (19)

22. The coefficient of x4 in the expansion of (1 + x + x2 + x3)6 in powers of x, is_______

Answer: (120)

23. Let the vectors,  such that  If the projection of  is equal to the projection of  is perpendicular to     is______

Answer: (6)

24. If the lines x+y = a and x-y = b touch the curve y = x2 − 3x + 2 at the points where the curve intersects the x-axis, then a/b is equal to______

Answer: (0.5)

25. In a bombing attack, there is 50% chance that a bomb will hit the target. At least two independent hits are required to destroy the target completely. Then the minimum number of bombs, that must be dropped to ensure that there is at least 99% chance of completely destroying the target, is_____

Answer: (11)

JEE Main September 5 2020 Shift 1 Question Paper with Answer Key

Physics

1. Three different processes that can occur in an ideal monatomic gas are shown in the P vs V diagram. The paths are labelled as A → B, A → C and A → D. The change in internal energies during these processes are taken as EAB, EAC and EAD and the work done as WAB, WAC and WAD. The correct relation between these parameters are:

(1)  EAB = EAC = EAD, WAB > 0, WAC = 0, WAD < 0

(2)  EAB > EAC > EAD, WAB < WAC < WAD

(3)  EAB < EAC < EAD, WAB > 0, WAC > WAD

(4)  EAB = EAC = EAD, WAB > 0, WAC = 0, WAD > 0

Answer: (1)

2. With increasing biasing voltage of a photodiode, the photocurrent magnitude :

(1)  increases initially and saturates finally

(2)  remains constant

(3)  increases linearly

(4)  increases initially and after attaining certain value, it decreases

Answer: (1)

3. A square loop of side 2a, and carrying current I, is kept in XZ plane with its centre at the origin. A long wire carrying the same current I is placed parallel to the z-axis and passing through the point (0, b, 0), (b > > a). The magnitude of the torque on the loop about the z-axis is given by:

(1) 

(2)    

(3)   

(4)   

Answer: (3)

4. Assume that the displacement (s) of air is proportional to the pressure difference (Δp) created by a sound wave. Displacement(s) further depends on the speed of sound (v), the density of air (⍴) and the frequency (f). If Δp ~ 10Pa, v ~ 300 m/s, ⍴ ~ 1 kg / m3 and f ~ 1000 Hz, then s will be of the order of (take the multiplicative constant to be 1)

(1)  1 mm

(2)  10 mm

(3)  1/10 mm

(4)  3/100 mm

Answer: (4)

5. Two capacitors of capacitances C and 2C are charged to potential differences V and 2V, respectively. These are then connected in parallel in such a manner that the positive terminal of one is connected to the negative terminal of the other. The final energy of this configuration is:

(1)  zero

(2)    

(3)   

(4)   

Answer: (4)

6. A helicopter rises from rest on the ground vertically upwards with a constant acceleration g. A food packet is dropped from the helicopter when it is at a height h. The time taken by the packet to reach the ground is close to [g is the acceleration due to gravity]:

(1)    

(2)   

(3)   

(4)   

Answer: (1)

7. A bullet of mass 5 g, travelling with a speed of 210 m/s, strikes a fixed wooden target. One half of its kinetic energy is converted into heat in the bullet while the other half is converted into heat in the wood. The rise of temperature of the bullet if the specific heat of its material is 0.030 cal/(g – °C) (1 cal = 4.2 × 107 ergs) close to:

(1)  38.4°C

(2)  87.5°C

(3)  83.3°C

(4)  119.2°C

Answer: (2)

8. A wheel is rotating freely with an angular speed on a shaft. The moment of inertia of the wheel is I and the moment of inertia of the shaft is negligible. Another wheel of the moment of inertia 3I initially at rest is suddenly coupled to the same shaft. The resultant fractional loss in the kinetic energy of the system is:

(1)  3/4

(2)  0

(3)  5/6

(4)  1/4

Answer: (1)

9. A balloon is moving up in air vertically above a point A on the ground. When it is at a height h1, a girl standing at a distance d(point B) from A (see figure) sees it at an angle 45° with respect to the vertical. When the balloon climbs up a further height h2, it is seen at an angle 60° with respect to the vertical if the girl moves further by a distance 2.464 d (point C). Then the height h2 is (given tan 30° = 0.5774):

(1)  0.464 d

(2)  d

(3)  0.732 d

(4)  1.464 d

Answer: (2)

10. An electrical power line, having a total resistance of 2Ω, delivers 1 kW at 220 V. The efficiency of the transmission line is approximately:

(1)  72%

(2)  91%

(3)  85%

(4)  96%

Answer: (4)

11. Activities of three radioactive substances A, B and C are represented by the curves A, B and C, in the figure. Then their half-lives T1/2 (A) : T1/2 (B) : T1/2 (C) are in the ratio:

(1)  3 : 2 : 1

(2)  2 : 1 : 1

(3)  4 : 3 : 1

(4)  2 : 1 : 3

Answer: (4)

12. The value of the acceleration due to gravity is g1 at a height h = R/ 2 (R = radius of the earth) from the surface of the earth. It is again equal to g1 at a depth d below the surface of the earth. The ratio (d / R) equals :

(1)  4/9

(2)  1/3

(3)  5/9

(4)  7/9

Answer: (3)

13. A hollow spherical shell at outer radius R floats just submerged under the water surface. The inner radius of the shell is r. If the specific gravity of the shell material is 27 / 8 w.r.t water, the value of r is:

(1)  4/9 R

(2)  8/9 R

(3)  1/3 R

(4)  2/3 R

Answer: (2)

14. In a resonance tube experiment when the tube is filled with water up to a height of 17.0 cm from the bottom, it resonates with a given tuning fork. When the water level is raised the next resonance with the same tuning fork occurs at a height of 24.5 cm. If the velocity of sound in air is 330 m/s, the tuning fork frequency is:

(1)  2200 Hz

(2)  550 Hz

(3)  3300 Hz

(4)  1100 Hz

Answer: (1)

15. A solid sphere of radius R carries a charge Q + q distributed uniformly over its volume. A very small point-like piece of it of mass m gets detached from the bottom of the sphere and falls down vertically under gravity. This piece carries charge q. If it acquires a speed v when it has fallen through a vertical height y (see figure), then : (assume the remaining portion to be spherical).

(1) 

(2)   

(3)    

(4)   

Answer: (1)

16. A galvanometer of resistance G is converted into a voltmeter of range 0 – 1V by connecting a resistance R1 in series with it. The additional resistance that should be connected in series with R1 to increase the range of the voltmeter to 0 – 2V will be:

(1)  G

(2)  R1

(3)  R1 – G

(4)  R1 + G

Answer: (4)

17. Number of molecules in a volume of 4 cm3 of a perfect monatomic gas at some temperature T and at a pressure of 2 cm of mercury is close to? (Given, mean kinetic energy of a molecule (at T) is 4 × 10–14 erg, g = 980 cm/s2, density of mercury = 13.6 g/cm3)

(1)  4.0 × 1018

(2)  4.0 × 106

(3)  5.8 × 1016

(4)  5.8 × 1018

Answer: (1)

18. An electron is constrained to move along the y-axis with a speed of 0.1 c (c is the speed of light) in the presence of electromagnetic wave, whose electric field is E = 30j sin (1.5 × 107 t – 5 × 10–2x) V/m. The maximum magnetic force experienced by the electron will be : (given c = 3 × 108 ms–1 and electron charge = 1.6 × 10–19C)

(1)  2.4 × 10–18 N

(2)  4.8 × 10–19 N

(3)  3.2 × 10–18 N

(4)  1.6 × 10–19 N

Answer: (2)

19. For a concave lens of focal length f, the relationship between object and image distances u and v, respectively, from its pole can best be represented by (u = is the reference line) :

Answer: (2)

20. A physical quantity z depends on four observables a, b, c and d, as  The percentages of error in the measurement of a, b, c and d are 2% , 1.5%, 4% and 2.5% respectively. The percentage of error in z is :

(1)  16.5%

(2)  12.25%

(3)  13.5%

(4)  14.5%

Answer: (4)

21. A particle of mass 200 Me V/c2 collides with a hydrogen atom at rest. Soon after the collision, the particle comes to rest, and the atom recoils and goes to its first excited state. The initial kinetic energy of the particle (in eV) is N/4. The value of N is : (Given the mass of the hydrogen atom to be 1 GeV/c2)_____.

Answer: (51)

22. Two concentric circular coils, C1 and C2, are placed in the XY plane. C1 has 500 turns, and a radius of 1 cm. C2 has 200 turns and a radius of 20 cm. C2 carries a time-dependent current I (t) = (5t2 – 2t + 3) A where t is in s. The emf induced in C1 (in mV), at the instant t = 1s is 4/x. The value of x is_____.

Answer: (5)

23. A beam of electrons of energy E scatters from a target having atomic spacing of 1Å. The first maximum intensity occurs at θ = 60° Then E (in eV) is ______. (Planck constant h = 6.64 × 10–34 Js, 1 eV = 1.6 × 10–19 J, electron mass m = 9.1 × 10–31 kg)

Answer: (50)

24. A compound microscope consists of an objective lens of focal length 1 cm and an eyepiece of focal length 5 cm with a separation of 10 cm. The distance between an object and the objective lens, at which the strain on the eye is minimum is n/40 cm. The value of n is _____.

Answer: (50)

25. A force  acts at a point Then the magnitude of torque about the point  will be √x N–m. The value of x is ______.

Answer: (195)

Chemistry

1. The potential energy curve for the H2 molecule as a function of internuclear distance is:

Answer: (2)

2.The most appropriate reagent for conversion of C2H5CN into CH3CH2CH2NH2 is:

(1)  NaBH4

(2)  Na(CN)BH3

(3)  CaH2

(4)  LIAlH4

Answer: (4)

3. Which of the following is not an essential amino acid?

(1)  Valine

(2)  Tyrosine

(3)  Lysine

(4)  Leucine

Answer: (2)

4. Which of the following derivatives of alcohols is unstable in an aqueous base?

Answer: (1)

5. The structure of PCl5 in the solid state is:

(1)  Square planar [PCl4]+ and octahedral [PCl6]

(2)  Tetrahedral [PCl4]+ and octahedral [PCl6]

(3)  Trigonal bipyramidal

(4)  Square pyramidal

Answer: (2)

6. A diatomic molecule X2 has a body-centred cubic (bcc) structure with a cell edge of 300 pm. The density of the molecule is 6.17 g cm–3. The number of molecules present in 200 g of X2 is:(Avogadro constant (NA) = 6 × 1023 mol–1)

(1)  8 NA

(2)  2 NA

(3)  40 NA

(4)  4 NA

Answer: (4)

7. The equation that represents the water-gas shift reaction is:

Answer: (1)

8. The increasing order of the acidity of the α-hydrogen of the following compounds

(1)  (D) < (C) < (A) < (B)

(2)  (A) < (C) < (D) < (B)

(3)  (C) < (A) < (B) < (D)

(4)  (B) < (C) < (A) < (D)

Answer: (1)

9. Indentify the correct molecular picture showing what happens at the critical micellar concentration (CMC) of an aqueous solution of a surfactant 

(1)  (B)

(2)  (A)

(3)  (C)

(4)  (D)

Answer: (4)

10. If a person is suffering from the deficiency of nor-adrenaline, what kind of drug can be suggested?

(1)  Antihistamine

(2)  Antidepressant

(3)  Anti-inflammatory

(4)  Analgesic

Answer: (2)

11. The values of the crystal field stabilization energies for a high spin d6 metal ion in octahedral and tetrahedral fields, respectively, are:

(1)  –2.4 Δ0 and –0.6 Δt

(2)  –1.6 Δ0 and –0.4 Δt

(3)  –0.4 Δ0 and –0.27 Δt

(4)  –0.4 Δ0 and –0.6 Δt

Answer: (4)

12. A flask contains a mixture of compounds A and B. Both compounds decompose by first order kinetics. The half-lives for A and B are 300 s and 180 s, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is: (Use ln 2 = 0.693)

(1)  180

(2)  300

(3)  120

(4)  900

Answer: (4)

13. The increasing order of basicity of the following compounds is:

(1)  (D) < (A) < (B) < (C)

(2)  (A) < (B) < (C) < (D)

(3)  (B) < (A) < (D) < (C)

(4)  (B) < (A) < (C) < (D)

Answer: (4)

14. The condition that indicates a polluted environment is:

(1)  pH of rain water to be 5.6

(2)  BOD value of 5 ppm

(3)  0.03% of CO2 in the atmosphere

(4)  eutrophication

Answer: (4)

15. In the sixth period, the orbitals that are filled are:

(1)  6s, 5d, 5f, 6p

(2)  6s, 4f, 5d, 6p

(3)  6s, 6p, 6d, 6f

(4)  6s, 5f, 6d, 6p

Answer: (2)

16. The difference between the radii of 3rd and 4th orbits of Li2+ is ΔR1. The difference between the radii of 3rd and 4th orbits of He+ is ΔR2. Ratio ΔR1: ΔR2 is:

(1)  8 : 3

(2)  3 : 8

(3)  3 : 2

(4)  2 : 3

Answer: (4)

17. In the following reaction sequence the major products A and B are:

Answer: (4)

18. The correct electronic configuration and spin-only magnetic moment (BM) of Gd3+ (Z = 64), respectively, are:

(1)  [Xe] 5f7 and 7.9

(2)  [Xe] 4f7 and 7.9

(3)  [Xe] 5f7 and 8.9

(4)  [Xe] 4f7 and 8.9

Answer: (2)

19. An Ellingham diagram provides information about:

(1)  The pressure dependence of the standard electrode potentials of reduction reactions involved in the extraction of metals.

(2)  The conditions of pH and potential under which a species is thermodynamically stable.

(3)  The kinetics of the reduction process.

(4)  The temperature dependence of the standard Gibbs energies of formation of some metal oxides.

Answer: (4)

20. Consider the following reaction:

N2O4(g) ⇌ 2NO2(g); ∆H° = +58 kJ

For each of the following cases (a, b), the direction in which the equilibrium shifts is:

(a) Temperature is decreased.

(b) Pressure is increased by adding N2 at constant T.

(1)  (a) towards reactant, (b) towards product

(2)  (a) towards reactant, (b) no change

(3)  (a) towards product, (b) towards reactant

(4)  (a) towards product, (b) no change

Answer: (2)

21. The minimum number of moles of O2 required for complete combustion of 1 mole of propane and 2 moles of butane is _____.

Answer: (18)

22. The number of chiral carbon(s) present in piptide, Iie-Arg-Pro, is ______ .

Answer: (4)

23. A soft drink was bottled with a partial pressure of CO2 of 3 bar over the liquid at room temperature. The partial pressure of CO2 over the solution approaches a value of 30 bar when 44 g of CO2 is dissolved in 1 kg of water at room temperature. The approximate pH of the soft drink is ______ × 10–1

(First dissociation constant of H2CO3= 4.0 × 10–7; log 2 = 0.3; density of the soft drink= 1 g mL–1)

Answer: (37)

24. An oxidation-reduction reaction in which 3 electrons are transferred has a ΔGº of 17.37 kJmol–1 at 250C. The value of E0cell (in V) is ______ × 10–2. (1 F = 96,500 C mol–1)

Answer: (6)

25. The total number of coordination sites in ethylenediaminetetraacetate (EDTA4–) is _____.

Answer: (6)

Mathematics

1. If the volume of a parallelopiped, whose coterminuous edges are given by the vectors  and  is 158 cu. units then:

(1) 

(2)   

(3)  n = 9

(4)  n = 7

Answer: (2)

2. A survey shows that 73% of the persons working in an office like coffee, whereas 65% like tea. If x denotes the percentage of them, who like both coffee and tea, then x cannot be:

(1)  63

(2)  54

(3)  38

(4)  36

Answer: (4)

3. The mean and variance of 7 observations are 8 and 16, respectively. If five observations are 2,4,10,12,14, then the absolute difference of the remaining two observations is:

(1)  1

(2)  4

(3)  3

(4)  2

Answer: (4)

4. If 210 + 29 × 31 + 28 × 32 +…..+ 2 × 39 + 310 = S−211, then S is equal to:

(1)  311

(2)   

(3)  2 ∙ 311

(4)  311 − 212

Answer: (1)

5. If 32 sin1,14 and 342sin2α are the first three terms of an A.P. for some α , then the sixth term of this A.P. is:

(1)  65

(2)  81

(3)  78

(4)  66

Answer: (4)

6. If the common tangent to the parabolas, y2 = 4x and x2 = 4y also touches the circle, x2 + y2 = c2, then c is equal to:

(1)  1/2

(2)  1/4

(3)  1/√2

(4)  1/2√2

Answer: (3)

7. If the minimum and the maximum values of the function  defined by  are m and M respectively, then the ordered pair (m, M) is equal to:

(1)  (0, 4)

(2)  (−4, 0)

(3)  (−4, 4)

(4)  (0, 2√2)

Answer: (2)

8. Let λ ∈ the system of linear equations

2x1 − 4x2 + λx3 = 1

x1 − 6x2 + x3 = 2

λx1 − 10x2 + 4x3 = 3

is inconsistent for:

(1)  exactly two values of λ

(2)  exactly one negative value of λ.

(3)  every value of λ.

(4)  exactly one positive value of λ.

Answer: (2)

9. If the point P on the curve, 4x2 + 5y2 = 20 is farthest from the point Q(0, −4), then PQ2 is equal to:

(1)  48

(2)  29

(3)  21

(4)  36

Answer: (4)

10. The product of the roots of the equation 9x2 – 18 |x| + 5 = 0 is :

(1)  25/81

(2)  5/9

(3)  5/27

(4)  25/9

Answer: (1)

11. If y = y(x) is the solution of the differential equation  satisfying y(0) = 1, then the value of y(loge 13) is:

(1)  1

(2)  0

(3)  2

(4)  −1

Answer: (4)

12. If S is the sum of the first 10 terms of the series  then tan(S) is equal to:

(1)  5/11

(2)  5/6

(3)  −6/5

(4)  10/11

Answer: (2)

13. The value of  is:

(1)  π/2

(2)  π/4

(3)  π

(4)  3π/2

Answer: (1)

14. If (a, b, c) is the image of the point (1,2,−3) in the line,  then a + b + c is

(1)  2

(2)  3

(3)  −1

(4)  1

Answer: (1)

15. If the function  is twice differentiable, then the ordered pair (k1, k2) is equal to:

(1)  (1, 1)

(2)  (1, 0)

(3)  (1/2, −1)

(4)  (1/2, 1)

Answer: (4)

16. If the four complex numbers  and z – 2Re(z) represent the vertices of a square of side 4 units in the Argand plane, then |z| is equal to:

(1)  2

(2)  4

(3)  4√2

(4)  2√2

Answer: (4)

17. If  where c is a constant of integration, then g(0) is equal to:

(1) 2           

(2)  e

(3)  1

(4)  e2

Answer: (1)

18. The negation of the Boolean expression x y is equivalent to:

(1)  (x˄y) ˄(∼x˅∼y)

(2)  (x˄y) ˅ (∼x˄∼y)

(3)  (x˄∼y) ˅ (∼x˄∼y)

(4)  (∼x˄y) ˅ (∼x˄∼y)

Answer: (2)

19. If α is positive root of the equation, p(x) = x2 – x – 2 = 0, then  is equal to :

(1)  1/2

(2)  3/√2

(3)  3/2

(4)  1/√2

Answer: (2)

20. If the co-ordinates of two points A and B are (√7, 0) and (−√7, 0) respectively and P is any point on the conic, 9x2 + 16y2 = 144, then PA+PB is equal to :

(1)  6

(2)  16

(3)  9

(4)  8

Answer: (4)

21. The natural number m, for which the coefficient of x in the binomial expansion of is  1540 is………….

Answer: (13)

22. Four fair dice are thrown independently 27 times. Then the expected number of times, at least two dice show up a three or a five, is……………

Answer: (11)

23. Let  for −10 < x < 10, where [t] denotes the greatest integer function. Then the number of points of discontinuity of f is equal to………….

Answer: (8)

24. The number of words, with or without meaning, that can be formed by taking 4 letters at a time from the letters of the word ’SYLLABUS’ such that two letters are distinct and two letters are alike, is

Answer: (240)

25. If the line, 2x − y + 3 = 0 is at a distance 1/√5 and 2/√5 from the lines 4x − 2y + α = 0 and 6x − 3y + β = 0, respectively, then the sum of all possible values of α and β is………………

Answer: (30)

JEE Main September 4 2020 Shift 2 Question Paper with Answer Key

Physics

1. A circular coil has moment of inertia 0.8 kg m2 around any diameter and is carrying current to produce a magnetic moment of 20 Am2. The coil is kept initially in a vertical position and it can rotate freely around a horizontal diameter. When a uniform magnetic field of 4 T is applied along the vertical, it starts rotating around its horizontal diameter. The angular speed the coil acquires after rotating by 60° will be:

(1)  10 π rad s–1

(2)  20 rad s–1

(3)  20 π rad s–1

(4)  10 rad s–1

Answer: (4)

2. A person pushes a box on a rough horizontal platform surface. He applies a force of 200 N over a distance of 15 m. Thereafter, he gets progressively tired and his applied force reduces linearly with distance to 100 N. The total distance through which the box has been moved is 30 m. What is the work done by the person during the total movement of the box?

(1)  5690 J

(2)  5250 J

(3)  2780 J

(4)  3280 J

Answer: (2)

3. Match the thermodynamic processes taking place in a system with the correct conditions. In the table: ∆Q is the heat supplied, ∆W is the work done and ∆U is change in internal energy of the system.

Process – Condition

(I) Adiabatic – (1) ∆W = 0

(II) Isothermal – (2) ∆ Q = 0

(III) Isochoric – (3) ∆U ≠0, ∆W ≠ 0, ∆Q ≠ 0

(IV) Isobaric – (4) ∆U = 0

(1)  (I) – (1), (II) – (1), (III) – (2), (IV) – (3)

(2)  (I) – (1), (II) – (2), (III) – (4), (IV) – (4)

(3)  (I) – (2), (II) – (4), (III) – (1), (IV) – (3)

(4)  (I) – (2), (II) – (1), (III) – (4), (IV) – (3)

Answer: (3)

4. The driver of a bus approaching a big wall notices that the frequency of his bus’s horn changes from 420 Hz to 490 Hz when he hears it after it gets reflected from the wall. Find the speed of the bus if speed of the sound is 330 ms–1.

(1)  81 kmh–1

(2)  91 kmh–1

(3)  71 kmh–1

(4)  61 kmh–1

Answer: (2)

5. A small ball of mass m is thrown upward with velocity u from the ground. The ball experiences a resistive force mkv2 where v is its speed. The maximum height attained by the ball is:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

6. Consider two uniform discs of the same thickness and different radii R1= R and R2 =αR made of the same material. If the ratio of their moments of inertia I1 and I2, respectively, about their axes is I1: I2 = 1 : 16 then the value of α is

(1)  √2

(2)  2

(3)  2√2

(4)  4

Answer: (2)

7. A series L-R circuit is connected to a battery of emf V. If the circuit is switched on at t =0, then the time at which the energy stored in the inductor reaches (1/n) times of its maximum value, is:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

8. The electric field of a plane electromagnetic wave is given by  Its magnetic field will be given  by:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

9. A cube of metal is subjected to a hydrostatic pressure of 4 GPa. The percentage change in the length of the side of the cube is close to: (Given bulk modulus of metal, B = 8 × 1010 Pa)

(1)  0.6

(2)  20

(3)  1.67

(4)  5

Answer: (3)

10. A paramagnetic sample shows a net magnetisation of 6 A/m when it is placed in an external magnetic field of 0.4 T at a temperature of 4 K. When the sample is placed in an external magnetic field of 0.3 T at a temperature of 24 K, then the magnetisation will be:

(1)  4 A/m

(2)  1 A/m

(3)  0.75 A/m

(4)  2.25 A/m

Answer: (3)

11. A body is moving in a low circular orbit about a planet of mass M and radius R. The radius of the orbit can be taken to be R itself. Then the ratio of the speed of this body in the orbit to the escape velocity from the planet is:

(1)  2

(2)  √2

(3)  1

(4)  1/√2

Answer: (4)

12. A particle of charge q and mass m is subjected to an electric field E = E0 (1 – ax2) in the x-direction, where a and E0 are constants. Initially the particle was at rest at x = 0. Other than the initial position the kinetic energy of the particle becomes zero when the distance of the particle from the origin is:

(1) 

(2)  a

(3) 

(4) 

Answer: (3)

13. A capacitor C is fully charged with voltage V0. After disconnecting the voltage source, it is connected in parallel with another uncharged capacitor of capacitance C/2. The energy loss in the process after the charge is distributed between the two capacitors is:

(1) 

(2) 

(3) 

(4) 

Answer: (2, 4)

14. Find the Binding energy per nucleon for  Mass of proton mp = 1.00783 U, mass of neutron mn = 1.00867 U and mass of tin nucleus mSn = 119.902199 U. (take 1U = 931 MeV)

(1)  8.0 MeV

(2)  9.0 MeV

(3)  7.5 MeV

(4)  8.5 MeV

Answer: (4)

15. The value of current i1 flowing from A to C in the circuit diagram is:

(1)  4 A

(2)  5 A

(3)  2 A

(4)  1 A

Answer: (4)

16. Two identical cylindrical vessels are kept on the ground and each contain the same liquid of density d. The area of the base of both vessels is S but the height of liquid in one vessel is x1 and in the other, x2. When both cylinders are connected through a pipe of negligible volume very close to the bottom, the liquid flows from one vessel to the other until it comes to equilibrium at a new height. The change in energy of the system in the process is:

(1)  gdS(x2 + x1)2

(2) 

(3) 

(4) 

Answer: (3)

17. A quantity x is given by (IFv2/WL4) in terms of moment of inertia I, force F, velocity v, work W and Length L. The dimensional formula for x is same as that of:

(1)  coefficient of viscosity

(2)  energy density

(3)  force constant

(4)  planck’s constant

Answer: (2)

18. For a uniform rectangular sheet shown in the figure, the ratio of moments of inertia about the axes perpendicular to the sheet and passing through O (the centre of mass) and O’ (corner point) is:

(1)  1/2

(2)  2/3

(3)  1/4

(4)  1/8

Answer: (3)

19. Identify the operation performed by the circuit given below:

(1)  NOT

(2)  OR

(3)  AND

(4)  NAND

Answer: (3)

20. In a photoelectric effect experiment, the graph of stopping potential V versus reciprocal of wavelength obtained is shown in the figure. As the intensity of incident radiation is increased:

(1)  Straight line shifts to right

(2)  Straight line shifts to left

(3)  Slope of the straight line get more steep

(4)  Graph does not change

Answer: (4)

21. The speed verses time graph for a particle is shown in the figure. The distance travelled (in m) by the particle during the time interval t = 0 to t = 5 s will be________.

Answer: (20)

22. Four resistances 40 Ω, 60 Ω, 90 Ω and 110 Ω make the arms of a quadrilateral ABCD. Across AC is a battery of emf 40 V and internal resistance negligible. The potential difference across BD in V is _______.

Answer: (2)

23. The change in the magnitude of the volume of an ideal gas when a small additional pressure ∆P is applied at a constant temperature, is the same as the change when the temperature is reduced by a small quantity ∆T at constant pressure. The initial temperature and pressure of the gas were 300 K and 2 atm. respectively. If │∆T│= C│∆ P│ then value of C in (K/atm.) is _________.

Answer: (150)

24. Orange light of wavelength 6000 × 10–10 m illuminates a single slit of width 0.6 × 10–4 The maximum possible number of diffraction minima produced on both sides of the central maximum is ___________.

Answer: (200)

25. The distance between an object and a screen is 100 cm. A lens can produce real image of the object on the screen for two different positions between the screen and the object. The distance between these two positions is 40 cm. If the power of the lens is close to (N/100)D where N is an integer, the value of N is _________.

Answer: (5)

Chemistry

1. The reaction in which the hybridisation of the underlined atom is affected is:

Answer: (2)

2. The process that is NOT endothermic in nature is :

(1)  H(g) + e → H(g)

(2)  Na(g) → Na(g) → e

(3)  Ar(g) + e → Ar(g)

(4)  O(g) + e → O(g)2−

Answer: (1)

3. If the equilibrium constant for  the equilibrium constant for A ⇌ P is:

Answer: (1)

4. A sample of red ink (a colloidal suspension) is prepared by mixing eosin dye, egg white, HCHO and water. The component which ensures the stability of the ink sample is :

(1)  HCHO

(2)  Water

(3)  Eosin dye

(4)  Egg white

Answer: (4)

5. The one that can exhibit the highest paramagnetic behaviour among the following is: gly = glycinato; bpy = 2, 2’-bipyridine

(1)  [Ti (NH3)6]3+

(2)  [Co (OX)2 (OH)2]

(3)  [Pd (gly)2]

(4)  [Fe (en) (bpy) (NH3)2]2+

Answer: (2)

6. Which of the following compounds will form the precipitate with aq. AgNO3 solution most readily?

Answer: (2)

7. Five moles of an ideal gas at 1 bar and 298 K is expanded into the vacuum to double the volume. The work done is:

(1)  zero

(2)  CV[T2 – T1]

(3)  −RT(V2 – V1)

(4)  −RT ln(V2/V1)

Answer: (1)

8. 250 mL of a waste solution obtained from the workshop of a goldsmith contains 0.1 M AgNO3 and 0.1 M AuCl. The solution was electrolyzed at 2 V by passing a current of 1 A for 15 minutes. The metal/metals electrodeposited will be:

(1)  Silver and gold in proportion to their atomic weights

(2)  Silver and gold in equal mass proportion

(3)  only silver

(4)  only gold

Answer: (1)

9. The mechanism of action of “Terfenadine” (Seldane) is:

(1)  Helps in the secretion of histamine

(2)  Activates the histamine receptor

(3)  Inhibits the secretion of histamine

(4)  Inhibits the action of histamine receptor

Answer: (4)

10. The shortest wavelength of the H atom in the Lyman series is λ1. The longest wavelength in the Balmer series of He+ is:

(1)  9λ1/5

(2)  27λ1/5

(3)  36λ1/5

(4)  5λ1/9

Answer: (1)

11. The major product [B] in the following reactions is:

Answer: (3)

12. The major product [C] of the following reaction sequence will be:

Answer: (1)

13. The Crystal Field Stabilization Energy (CFSE) of [CoF3(H2O)3] (Δ0 < P) is:

(1)  – 0.8Δ0

(2)  – 0.8Δ0 + 2P

(3)  – 0.4Δ0 + P

(4)  – 0.4Δ0

Answer: (4)

14. Among the following compounds, which one has the shortest C – Cl bond?

Answer: (4)

15. The major product [R] in the following sequence of reactions is:

Answer: (2)

16. The molecule in which hybrid AOs involve only one d-orbital of the central atom is:

(1)  [CrF6]3

(2)  XeF4

(3)  BrF5

(4)  [Ni(CN)4]2

Answer: (4)

17. In the following reaction sequence, [C] is:

Answer: (3)

18. The processes of calcination and roasting in metallurgical industries, respectively, can lead to:

(1)  Photochemical smog and ozone layer depletion

(2)  Photochemical smog and global warming

(3)  Global warming and photochemical smog

(4)  Global warming and acid rain

Answer: (4)

19. The incorrect statement(s) among (a) – (c) is (are):

(a) W(VI) is more stable than Cr(VI).

(b) in the presence of HCl, permanganate titrations provide satisfactory results.

(c) some lanthanoid oxides can be used as phosphors.

(1)  (a) only

(2)  (b) and (c) only

(3)  (a) and (b) only

(4)  (b) only

Answer: (4)

20. An alkaline earth metal ‘M’ readily forms water-soluble sulphate and water-insoluble hydroxide. Its oxide MO is very stable to heat and does not have a rock-salt structure. M is :

(1)  Ca

(2)  Be

(3)  Mg

(4)  S

Answer: (2)

21. The osmotic pressure of a solution of NaCl is 0.10 atm and that of a glucose solution is 0.20 atm. The osmotic pressure of a solution formed by mixing 1 L of the sodium chloride solution with 2 L of the glucose solution is x × 103 x is _______. (nearest integer)

Answer: (167)

22. The number of molecules with energy greater than the threshold energy for a reaction increases fivefold by a rise of temperature from 27°C to 42 °C. Its energy of activation in J/mol is ________. (Take ln 5 = 1.6094 ; R = 8.314 J mol1K1)

Answer: (84297.47)

23. A 100 mL solution was made by adding 1.43 g of Na2CO3 . xH2 The normality of the solution is 0.1 N. The value of x is ________. (The atomic mass of Na is 23 g/mol).

Answer: (10)

24. Consider the following equations:

2 Fe2+ + H2O2 → x A + y B (in basic medium)

2 MnO4 + 6 H+ + 5 H2O2 → x ‘C + y ‘D + z’E (in acidic medium).

The sum of the stoichiometric coefficients x, y, x’,y’ and z’ for products A, B, C, D and E, respectively, is _________.

Answer: (19)

25. The number of chiral centres present in threonine is ________.

Answer: (2)

Mathematics

1. Suppose the vectors x1, x2 and x3 are the solutions of the system of linear equations, Ax = b when the vector b on the right side is equal to b1, b2 and b3 If  then the determinant of A is equal to

(1)  2

(2)  1/2

(3)  3/2

(4)  4

Answer: (1)

2. If a and b are real numbers such that (2+α)4 = a + bα, where  then a + b is equal to:

(1)  33

(2)  57

(3)  9

(4)  24

Answer: (3)

3. The distance of the point (1, −2, 3) from the plane x – y + z = 5 measured parallel to the line  is:

(1)  1/7

(2)  7

(3)  7/5

(4)  1

Answer: (4)

4. Let f: (0, ∞) → (0, ∞) be a differentiable function such that f(1) = e and  If f(x) = 1, then x is equal to:

(1)  e

(2)  2e

(3)  1/e

(4)  1/2e

Answer: (3)

5. Contra positive of the statement :

‘If a function f is differentiable at a, then it is also continuous at a’, is:

(1)  If a function f is not continuous at a, then it is not differentiable at a.

(2)  If a function f is continuous at a, then it is differentiable at a.

(3)  If a function f is continuous at a, then it is not differentiable at a.

(4)  If a function f is not continuous at a, then it is differentiable at a.

Answer: (1)

6. The minimum value of 2sinx + 2cosx is:

(1)  21 – 2

(2)  21 – 1/2

(3)  2– 1 + 2

(4)  2–1 + 1/2

Answer: (2)

7. If the perpendicular bisector of the line segment joining the points P(1 ,4) and Q(k, 3) has y-intercept equal to −4, then a value of k is:

(1)  −2

(2)  √15

(3)  √14

(4)  −4

Answer: (4)

8. The area (in sq. units) of the largest rectangle ABCD whose vertices A and B lie on the x-axis and vertices C and D lie on the parabola, y = x2 − 1 below the x-axis, is:

(1)  2/3√3

(2)  4/3

(3)  1/3√3

(4)  4/3√3

Answer: (4)

9. The integral  (2 sec2x ∙ sin2 3x + 3 tan x ∙ sin 6x) dx is equal to:

(1)  9/2

(2)  −1/18

(3)  −1/9

(4)  7/18

Answer: (2)

10. If the system of equations

x + y + z = 2

2x + 4y – z = 6

3x + 2y + λz = μ

has infinitely many solutions, then

(1)  λ −2μ = -5

(2)  2λ + μ = 14

(3)  λ + 2μ = 14

(4)  2λ – μ = 5

Answer: (2)

11. In a game two players A and B take turns in throwing a pair of fair dice starting with player A and total of scores on the two dice, in each throw is noted. A wins the game if he throws a total of 6 before B throws a total of 7 and B wins the game if he throws a total of 7 before A throws a total of six The game stops as soon as either of the players wins. The probability of A winning the game is :

(1)  5/31

(2)  31/61

(3)  30/61

(4)  5/6

Answer: (3)

12. If for some positive integer n, the coefficients of three consecutive terms in the binomial expansion of (1 + x)n+5 are in the ratio 5:10:14, then the largest coefficient in this expansion is :

(1)  792

(2)  252

(3)  462

(4)  330

Answer: (3)

13. The function  is:

(1)  both continuous and differentiable on R−{−1}

(2)  continuous on R−{−1} and differentiable on R−{−1,1}

(3)  continuous on R−{1} and differentiable on R−{−1, 1}

(4)  both continuous and differentiable on R−{1}

Answer: (3)

14. The solution of the differential equation  is: (where c is a constant of integration)

(1)  x – loge(y + 3x) = C

(2) 

(3)  x – 2loge(y + 3x) = C

(4) 

Answer: (2)

15. Let λ ≠ 0 be in R. If α and β are the roots of the equation, x2 – x + 2λ = 0 and α and γ are the roots of the equation, 3x2 − 10x + 27λ = 0, then βγ/λ is equal to:

(1)  27

(2)  9

(3)  18

(4)  36

Answer: (3)

16. The angle of elevation of a cloud C from a point P, 200 m above a still lake is 30°. If the angle of depression of the image of C in the lake from the point P is 60°, then PC (in m) is equal to :

(1)  200√3

(2)  400√3

(3)  400

(4)  100

Answer: (3)

17. Let  where each Xi contains 10 elements and each Yi contains 5 elements. If each element of the set T is an element of exactly 20 of sets Xi ’s and exactly 6 of sets Yi’s, then n is equal to :

(1)  15

(2)  30

(3)  50

(4)  45

Answer: (2)

18. Let x = 4 be a directrix to an ellipse whose centre is at the origin and its eccentricity is 1/2. If P(1, β ), β > 0 is a point on this ellipse, then the equation of the normal to it at P is :

(1)  8x – 2y = 5

(2)  4x – 2y = 1

(3)  7x – 4y = 1

(4)  4x – 3y = 2

Answer: (2)

19. Let a1, a2, …, an be a given A.P. whose common difference is an integer and Sn = a1 + a2 + …. + an. If a1 = 1, an = 300 and 15 ≤ n ≤ 50, then the ordered pair (Sn4, an4) is equal to:

(1)  (2480, 248)

(2)  (2480, 249)

(3)  (2490, 249)

(4)  (2490, 248)

Answer: (4)

20. The circle passing through the intersection of the circles, x2 + y2 − 6x = 0 and x2 + y2 − 4y = 0, having its centre on the line, 2x − 3y + 12 = 0, also passes through the point:

(1)  (−1, 3)

(2)  (1, −3)

(3)  (−3, 6)

(4)  (−3, 1)

Answer: (3)

21. Let {x} and [x] denote the fractional part of x and the greatest integer ≤ x respectively of a real number x. If and 10(n2 – n), (n ∈ N, n > 1) are three consecutive terms of a G.P., then n is equal to______

Answer: (21)

22. A test consists of 6 multiple choice questions, each having 4 alternative answers of which only one is correct. The number of ways, in which a candidate answers all six questions such that exactly four of the answers are correct, is______

Answer: (135)

23. If  then the value of  is equal to ______

Answer: (18)

24. Let PQ be a diameter of the circle x2 + y2 = 9. If α and β are the lengths of the perpendiculars from P and Q on the straight line, x + y = 2 respectively, then the maximum value of αβ is____

Answer: (7)

25. If the variance of the following frequency distribution :

Class                      :           10-20   20-0     30-40

Frequency             :           2             x           2

is 50, then x is equal to _______

Answer: (4)

JEE Main September 4 2020 Shift 1 Question Paper with Answer Key

Physics

1. Starting from the origin at time t = 0, with initial velocity  a particle moves in the x-y plane with a constant acceleration of  At time t, its coordinates are (20 m, y0 m). The values of t and y0 are, respectively:

(1)  5s and 25 m

(2)  2s and 18 m

(3)  2s and 24 m

(4)  4s and 52 m

Answer: (2)

2. A small bar magnet placed with its axis at 30° with an external field of 0.06 T experiences a torque of 0.018 Nm. The minimum work required to rotate it from its stable to unstable equilibrium position is:

(1)  7.2 × 102 J

(2)  6.4 × 102 J

(3)  9.2 × 103 J

(4)  11.7 × 103 J

Answer: (1)

3.Choose the correct option relating wave lengths of different parts of electromagnetic wave spectrum:

(1)  λradio waves > λmicro waves > λvisible > λx-rays

(2)  λvisible > λx-rays > λradio waves > λmicro waves

(3)  λvisible < λmicro waves < λradio waves < λx-rays

(4)  λx-rays < λmicro waves < λradio waves < λvisible

Answer: (1)

4. On the x-axis and at a distance x from the origin, the gravitational field due a mass distribution is given by  in the x-direction. The magnitude of gravitational potential on the x-axis at a distance x, taking its value to be zero at infinity, is:

(1)  A(x2 + a2)3/2

(2) 

(3)  A(x2 + a2)1/2

(4) 

Answer: (2)

5. A small bar magnet is moved through a coil at constant speed from one end to the other. Which of the following series of observations will be seen on the galvanometer G attached across the coil?

Answer: (1)

6. A battery of 3.0V is connected to a resistor dissipating 0.5 W of power. If the terminal voltage of the battery is 2.5V, the power dissipated within the internal resistance is:

(1)  0.072 W

(2)  0.10 W

(3)  0.125 W

(4)  0.50 W

Answer: (2)

7. Two charged thin infinite plane sheets of uniform surface charge density σ + and σ –, where| σ+| > |σ|, intersects at right angle. Which of the following best represents the electric field lines for this system?

Answer: (1)

8. An air bubble of radius 1 cm in water has an upward acceleration 9.8 cm s–2. The density of water is 1 gm cm–3 and water offers negligible drag force on the bubble. The mass of the bubble is (g = 980 cm/s2).

(1)  1.52 gm

(2)  4.51 gm

(3)  3.15 gm

(4)  4.15 gm

Answer: (4)

9. A wire A, bent in the shape of an arc of a circle, carrying a current of 2A and having radius 2 cm and another wire B, also bent in the shape of arc of a circle, carrying a current of 3 A and having radius of 4 cm, are placed as shown in the figure. The ratio of the magnetic field due to the wires A and B at the common centre O is:

(1)  2 : 5

(2)  6 : 5

(3)  6 : 4

(4)  4 : 6

Answer: (2)

10. Particle A of mass mA=m/2 moving along the x-axis with velocity v0 collides elastically with another particle B at rest having mass mB = m/3. If both particles move along the x-axis after the collision, the change ∆λ in de-Broglie wavelength of particle A, in terms of its de-Broglie wavelength (λ0) before collision is:

(1) 

(2)  ∆λ = 2λ0

(3)  ∆λ = 4λ0

(4) 

Answer: (3)

11. Blocks of masses m, 2m, 4m and 8m are arranged in a line on a frictionless floor. Another block of mass m, moving with speed v along the same line (see figure) collides with mass m in perfectly inelastic manner. All the subsequent collisions are also perfectly inelastic. By the time the last block of mass 8m starts moving the total energy loss is p% of the original energy. Value of ‘p’ is close to:

(1)  94

(2)  87

(3)  37

(4)  77

Answer: (1)

12. Given figure shows few data points in a photo-electric effect experiment for a certain metal. The minimum energy for ejection of electron from its surface is: (Planck’s constant h = 6.62 × 10–34s)

(1)  2.10 eV

(2)  2.27 eV

(3)  2.59 eV

(4)  1.93 eV

Answer: (2)

13. The specific heat of water = 4200 J kg–1K–1 and the latent heat of ice = 3.4 × 105 J kg1.100 grams of ice at 0°C is placed in 200 g of water at 25°C. The amount of ice that will melt as the temperature of water reaches 0°C is close to (in grams):

(1)  63.8

(2)  64.6

(3)  61.7

(4)  69.3

Answer: (3)

14. A beam of plane polarised light of large cross-sectional area and uniform intensity of 3.3 Wm–2 falls normally on a polariser (cross sectional area 3 × 10–4 m2) which rotates about its axis with an angular speed of 31.4 rad/s. The energy of light passing through the polariser per revolution is close to:

(1)  1.0 × 104 J

(2)  1.0 × 105 J

(3)  5.0 × 104 J

(4)  1.5 × 104 J

Answer: (1)

15. For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5m, while the distance between one crest and one trough is 1.5m. The possible wavelengths (in m) of the waves are:

(1)  1, 3, 5,…..

(2)  1, 2, 3,……

(3)  1/2, 1/4, 1/6…..

(4)  1/1, 1/3, 1/5…..

Answer: (4)

16. Match the CP/CV ratio for ideal gases with different type of molecules:

Answer: (4)

17. Two points charges 4q and –q are fixed on the x-axis at x = −(d/2) and x = (d/2), respectively. If a third point charge ‘q’ is taken from the origin to x = d along the semicircle as shown in the figure, the energy of the charge will:

(1)  decrease by q2/4π∈0d

(2)  decrease by 4q2/3π∈0d

(3)  increase by 3q2/4π∈0d

(4)  increase by 2q2/3π∈0d

Answer: (2)

18. A Tennis ball is released from a height h and after freely falling on a wooden floor it rebounds and reaches height h/2. The velocity versus height of the ball during its motion may be represented graphically by: (graphs are drawn schematically and are not to scale)

Answer: (1)

19. Dimensional formula for thermal conductivity is (here K denotes the temperature):

(1)  MLT3K1

(2)  MLT2K2

(3)  MLT2K

(4)  MLT3K

Answer: (1)

20. Take the breakdown voltage of the zener diode used in the given circuit as 6V. For the input voltage shown in figure below, the time variation of the output voltage is : (Graphs drawn are schematic and not to scale)

Answer: (3)

21. In the line spectra of hydrogen atoms, difference between the largest and the shortest wavelengths of the Lyman series is 304Å. The corresponding difference for the Paschen series in Å is : ___________.

Answer: (10553)

22. A closed vessel contains 0.1 mole of a monoatomic ideal gas at 200 K. If 0.05 mole of the same gas at 400 K is added to it, the final equilibrium temperature (in K) of the gas in the vessel will be close to _______.

Answer: (267)

23. ABC is a plane lamina of the shape of an equilateral triangle. D, E are mid points of AB, AC and G is the centroid of the lamina. Moment of inertia of the lamina about an axis passing through G and perpendicular to the plane ABC is I0. If part ADE is removed, the moment of inertia of the remaining part about the same axis is NI0 /16 where N is an integer. Value of N is _____________.

Answer: (11)

24. In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eye-piece. The focal length of its objective lens is 1 cm. If the magnification is 100 and the tube length of the microscope is 20 cm, then the focal length of the eyepiece lens (in cm) is __________.

Answer: (6.25)

25. A circular disc of mass M and radius R is rotating about its axis with angular speed ω1. If another stationary disc having radius R/2 and same mass M is dropped co-axially on to the rotating disc. Gradually both discs attain constant angular speed ω2. The energy lost in the process is p% of the initial energy. Value of p is __________.

Answer: (20)

Chemistry

1. The IUPAC name of the following compound is:

(1)  3-Bromo-5-methyl cyclopentane carboxylic acid

(2)  4-Bromo-2-methyl cyclopentane carboxylic acid

(3)  5-Bromo-3-methyl cyclopentanoic acid

(4)  3-Bromo-5-methyl cyclopentanoic acid

Answer: (2)

2. On heating, lead(II) nitrate gives a brown gas (A). The gas (A) on cooling changes to a colourless solid/liquid (B). (B) on heating with NO changes to a blue solid (C). The oxidation number of nitrogen in solid (C) is:

(1)  +3

(2)  +4

(3)  +2

(4)  +5

Answer: (1)

3. The ionic radii of O2–, F, Na+ and Mg2+ are in the order:

(1)  F > O2– > Na+ > Mg2+

(2)  Mg2+ > Na+ > F > O2

(3)  O2– > F > Na+ > Mg2+

(4)  O2– > F > Mg2+ > Na+

Answer: (3)

4. When neopentyl alcohol is heated with an acid, it is slowly converted into an 85:15 mixture of alkenes A and B, respectively. What are these alkenes?

Answer: (3)

5. The region in the electromagnetic spectrum where the Balmer series lines appear is:

(1)  Microwave

(2)  Infrared

(3)  Ultraviolet

(4)  Visible

Answer: (4)

6. Identify the incorrect statement from the options below for the above cell:

(1)  If Eext = 1.1 V, no flow of e or current occurs

(2)  If Eext > 1.1 V, Zn dissolves at Zn electrode and Cu deposits at Cu electrode

(3)  If Eext > 1.1 V, e flow from Cu to Zn

(4)  If Eext < 1.1 V, Zn dissolves at the anode and Cu deposits at the cathode

Answer: (2)

7. What are the functional groups present in the structure of maltose?

(1)  One acetal and one hemiacetal

(2)  One acetal and one ketal

(3)  One ketal and one hemiketal

(4)  Two acetals

Answer: (1)

8. Match the following:

(i) Foam                (a) smoke

(ii) Gel                   (b) cell fluid

(iii) Aerosol          (c) jellies

(iv) Emulsion       (d) rubber

                                (e) froth

                                (f) milk

(1)  (i)-(e), (ii)-(c), (iii)-(a), (iv)-(f)

(2)  (i)-(b), (ii)-(c), (iii)-(e), (iv)-(d)

(3)  (i)-(d), (ii)-(b), (iii)-(a), (iv)-(e)

(4)  (i)-(d), (ii)-(b), (iii)-(e), (iv)-(f)

Answer: (1)

9. An organic compound (A) (molecular formula C6H12O2) was hydrolysed with dilute H2SO4 to give a carboxylic acid (B) and alcohol (C). ‘C’ gives white turbidity immediately when treated with anhydrous ZnCl2 and conc. HCl. The organic compound (A) is:

Answer: (4)

10. Among the statements (a)-(d), the correct ones are:

(a) Limestone is decomposed to CaO during the extraction of iron from its oxides.

(b) In the extraction of silver, silver is extracted as an anionic complex.

(c) Nickel is purified by Mond’s process.

(d) Zr and Ti are purified by Van Arkel method.

(1)  (c) and (d) only

(2)  (b), (c) and (d) only

(3)  (a), (b), (c) and (d)

(4)  (a), (c) and (d) only

Answer: (3)

11. For one mole of an ideal gas, which of these statements must be true?

(a) U and H each depends only on temperature

(b) Compressibility factor z is not equal to 1

(c) CP,m – CV,m = R

(d) dU = CV dT for any process

(1)  (a), (c) and (d)

(2)  (a) and (c)

(3)  (c) and (d)

(4)  (b), (c) and (d)

Answer: (1)

12. [P] on treatment with Br2/FeBr3 in CCl4 produced a single isomer C8H7O2Br while heating [P] with soda lime gave toluene. The compound [P] is:

Answer: (2)

13. For the equilibrium A ⇌ B the variation of the rate of the forward (a) and reverse (b) reaction with time is given by :

Answer: (2)

14. The pair in which both the species have the same magnetic moment (spin only) is:

(1)  [Co(OH)4]2– and [Fe(NH3)6]2+

(2)  [Mn(H2O)6]2+ and [Cr(H2O)]2+

(3)  [Cr(H2O)6]2+ and [CoCl4]2–

(4)  [Cr(H2O)6]2+ and [Fe(H2O)6]2+

Answer: (4)

15. The number of isomers possible for [Pt(en)(NO2)2] is:

(1)  2

(2)  3

(3)  4

(4)  1

Answer: (2)

16. The decreasing order of reactivity of the following organic molecules towards the AgNO3 solution is:

(1)  (B) > (A) > (C) > (D)

(2)  (A) > (B) > (C) > (D)

(3)  (A) > (B) > (D) > (C)

(4)  (C) > (D) > (A) > (B)

Answer: (1)

17. The intermolecular potential energy for the molecules A, B, C and D given below suggests that:

(1)  A–A has the largest bond enthalpy.

(2)  D is more electronegative than other atoms.

(3)  A–D has the shortest bond length.

(4)  A–B has the stiffest bond.

Answer: (4)

18. Which of the following will react with CHCl3 + alc. KOH?

(1)  Thymine and proline

(2)  Adenine and thymine

(3)  Adenine and lysine

(4)  Adenine and proline

Answer: (3)

19. The elements with atomic numbers 101 and 104 belong to, respectively:

(1)  Actinoids and Group 6

(2)  Group 11 and Group 4

(3)  Group 6 and Actinoids

(4)  Actinoids and Group 4

Answer: (4)

20. On combustion of Li, Na and K in excess of air, the major oxides formed, respectively, are :

(1)  Li2O2, Na2O2 and K2O2

(2)  Li2O, Na2O2 and KO2

(3)  Li2O, Na2O and K2O2

(4)  Li2O, Na2O2 and K2O

Answer: (2)

21. The number of chiral centres present in [B] is ________.

Answer: (4)

22. At 300 K, the vapour pressure of a solution containing 1 mole of n-hexane and 3 moles of n-heptane is 550 mm of Hg. At the same temperature, if one more mole of n-heptane is added to this solution, the vapour pressure of the solution increases by 10 mm of Hg. What is the vapour pressure in mm of Hg of n-heptane in its pure state _______?

Answer: (600)

23. The mass of ammonia in grams produced when 2.8 kg of dinitrogen quantitatively reacts with 1 kg of dihydrogen is _________.

Answer: (3400)

24. If 75% of a first order reaction was completed in 90 minutes, 60% of the same reaction would be completed in approximately (in minutes) ________. (take : log 2 = 0.30; log 2.5 = 0.40)

Answer: (60)

25. A 20.0 mL solution containing 0.2 g impure H2O2 reacts completely with 0.316 g of KMnO4 in acid solution. The purity of H2O2 (in %) is _______ (mol. wt. of H2O2 = 34’ mole wt. of KMnO4 = 158)

Answer: (85)

Mathematics

1. Let y = y(x) be the solution of the differential equation, xy’− y = x2(x cos x + sin x), x > 0. If y(π) = π, then  is equal to

(1) 

(2) 

(3) 

(4) 

Answer: (2)

2. The value of  is equal to:

(1)  51C730C7

(2)  51C7 + 30C7

(3)  50C730C7

(4)  50C630C6

Answer: (1)

3. Let [t] denote the greatest integer ≤ t. Then the equation in x, [x]2 + 2[x + 2] − 7 = 0 has:

(1)  exactly four integral solutions.

(2)  infinitely many solutions.

(3)  no integral solution.

(4)  exactly two solutions.

Answer: (2)

4. Let P(3, 3) be a point on the hyperbola,  If the normal to it at P intersects the x-axis at (9, 0) and e is its eccentricity, then the ordered pair (a2, e2) is equal to:

(1)  (9, 3)

(2)  (9/2, 2)

(3)  (9/2, 3)

(4)  (3/2, 2)

Answer: (3)

5. Let  be a given ellipse, length of whose latus rectum is 10. If its eccentricity is the maximum value of the function,   then a2 + b2 is equal to

(1)  135

(2)  116

(3)  126

(4)  145

Answer: (3)

6. Let  Then f(3) – f(1) is equal to:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

7. If 1 + (1 − 22 × 1) + (1 − 42 × 3) + (1 − 62 × 5) + …… + (1 − 202 × 19) = α – 220 β, then an ordered pair (α, β) is equal to:

(1)  (10, 97)

(2)  (11, 103)

(3)  (11, 97)

(4)  (10, 103)

Answer: (2)

8. The integral  is equal to

(where C is a constant of integration):

(1) 

(2) 

(3) 

(4) 

Answer: (1)

9. Let f(x) = |x – 2| and g(x) = f(f(x)), x ∈ [0, 4]. Then  is equal to:

(1)  1/2

(2)  0

(3)  1

(4)  3/2

Answer: (3)

10. Let x0 be the point of local maxima of  where   and  Then the value of  at x = x0 is :

(1)  2

(2)  −4

(3)  −30

(4)  14

Answer: (1)

11. A triangle ABC lying in the first quadrant has two vertices as A(1, 2) and B(3, 1). If ∠BAC = 90° and ar(ΔABC) = 5√5 s units, then the abscissa of the vertex C is:

(1)  1 + √5

(2)  1 + 2√5

(3)  2√5 − 1

(4)  2 + √5

Answer: (2)

12. Let f be a twice differentiable function on (1,6). If f(2) = 8, f´(2) = 5, f´(x) ≥ 1 and f´´(x) ≥ 4, for all x ∈ (1, 6), then:

(1)  f(5) + f´(5) ≥ 28

(2)  f´(5) + f´´(5) ≤ 20

(3)  f(5) ≤ 10

(4)  f(5) + f´(5) ≤ 26

Answer: (1)

13. Let α and β be the roots of x2 − 3x + p = 0 and γ and δ be the roots of x2 − 6x + q = 0. If α, β, γ, δ form a geometric progression. Then ratio (2q + p): (2q − p) is:

(1)  33: 31

(2)  9: 7

(3)  3 : 1

(4)  5 :3

Answer: (2)

14. Let  z = x + iy and k > 0. If the curve represented by Re(u) + Im(u) =1 intersects the y-axis at the points P and Q where PQ =5, then the value of k is:

(1)  4

(2)  1/2

(3)  2

(4)  3/2

Answer: (3)

15. If and  where i = √−1 then which one of the following is not true?

(1)  a2 – d2 = 0

(2)  a2 – c2 = 1

(3)  0 ≤ a2 + b2 ≤ 1

(4)  a2 – b2 = 1/2

Answer: (4)

16. The mean and variance of 8 observations are 10 and 13.5, respectively. If 6 of these observations are 5, 7, 10, 12, 14, 15, then the absolute difference of the remaining two observations is:

(1)  3

(2)  9

(3)  7

(4)  5

Answer: (3)

17. A survey shows that 63% of the people in a city read newspaper A whereas 76% read newspaper B. If x% of the people read both the newspapers, then a possible value of x can be:

(1)  37

(2)  29

(3)  65

(4)  55

Answer: (4)

18. Given the following two statements

(S1): (q˅p)→(p ↔ ~q) is a tautology.

(S2): ~q ˄ (~p ↔ q) is a fallacy. Then:

(1) only (S1) is correct.

(2)  both (S1) and (S2) are correct.

(3)  only (S2) is correct

(4)  both (S1) and (S2) are not correct.

Answer: (4)

19. Two vertical poles AB = 15 m and CD = 10 m are standing apart on a horizontal ground with points A and C on the ground. If P is the point of intersection of BC and AD, then the height of P (in m) above the line AC is:

(1)  5

(2)  20/3

(3)  10/3

(4)  6

Answer: (4)

20. If (a + √2b cos x)( a − √2b cos y) = a2 − b2, where a > b > 0, then  is:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

21. Suppose a differentiable function f(x) satisfies the identity f(x + y) = f(x) + f(y) + xy2 + x2y,for all real x and y. If  then f´(3) is equal to…………

Answer: (10)

22. If the equation of a plane P, passing through the intersection of the planes, x + 4y – z + 7 = 0 and 3x + y + 5z = 8 is ax + by + 6z = 15 for some a, b ∈ R, then the distance of the point (3, 2, −1) from the plane P is ….. units.

Answer: (3)

23. If the system of equations

x – 2y + 3z = 9

2x + y + z = b

x – 7y + az = 24, has infinitely many solutions, then a – b is equal to…………..

Answer: (5)

24. Let  Then a7/a13 is equal to………..

Answer: (8)

25. The probability of a man hitting a target is 1/10. The least number of shots required, so that the probability of his hitting the target at least once is greater than 1/4 is……….

Answer: (3)

JEE Main September 3 2020 Shift 2 Question Paper with Answer Key

Physics

1. A block of mass m attached to a massless spring is performing oscillatory motion of amplitude ‘A’ on a frictionless horizontal plane. If half of the mass of the block breaks off when it is passing through its equilibrium point, the amplitude of oscillation for the remaining system become fA. The value of f is:

(1)  1/√2

(2)  1/2

(3)  1

(4)  √2

Answer: (4)

2. The mass density of a planet of radius R varies with the distance r from its centre as  Then the gravitational field is maximum at:

(1) 

(2) 

(3)  r = R

(4) 

Answer: (4)

3. Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. The ratio of the number density of photons of X-rays to the number density of photons of the visible light of the given wavelengths is:

(1)  1/500

(2)  1/250

(3)  500

(4)  250

Answer: (1)

4. If a semiconductor photodiode can detect a photon with a maximum wavelength of 400nm, then its band gap energy is : Planck’s constant h = 6.63 × 10–34s. Speed of light c = 3 × 108 m/s

(1)  1.5 eV

(2)  2.0 eV

(3)  3.1 eV

(4)  1.1 eV

Answer: (3)

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5. Amount of solar energy received on the earth’s surface per unit area per unit time is defined a solar constant. Dimension of solar constant is:

(1)  ML0T3

(2)  MLT2

(3)  M2L0T1

(4)  ML2T2

Answer: (1)

6. A particle is moving unidirectionally on a horizontal plane under the action of a constant power supplying energy source. The displacement (s) – time (t) graph that describes the motion of the particle is (graphs are drawn schematically and are not to scale:

Answer: (2)

7. Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed?

(1)  Multimeter shows NO deflection in both cases i.e. before and after reversing the probes if the chosen component is metal wire.

(2)  Multimeter shows a deflection, accompanied by a splash of light out of connected component in one direction and NO deflection on reversing the probes if the chosen component is LED.

(3)  Multimeter shows an equal deflection in both cases i.e. before and after reversing the probes if the chosen component is resistor.

(4)  Multimeter shows NO deflection in both cases i.e. before and after reversing the probes if the chosen component is capacitor.

Answer: (4)

8. A uniform rod of length ‘l’ is pivoted at one of its ends on a vertical shaft of negligible radius. When the shaft rotates at angular speed ω the rod makes an angle θ with it (see figure). To find θ equate the rate of change of angular momentum (direction going into the paper)  about the centre of mass (CM) to the torque provided by the horizontal and vertical forces FH and FV about the CM. The value of θ is then such that:

(1)  cos θ = 2g/3l ω2

(2)  cos θ = 3g/2l ω2

(3)  cos θ = g/2l ω2

(4)  cos θ = g/I ω2

Answer: (2)

9. Two resistors 400 Ω and 800 Ω are connected in series across a 6 V battery. The potential difference measured by a voltmeter of 10 k Ω across 400 Ω resistors is close to:

(1)  2.05 V

(2)  2 V

(3)  1.95 V

(4)  1.8 V

Answer: (3)

10. A block of mass 1.9 kg is at rest at the edge of a table, of height 1 m. A bullet of mass 0.1 kg collides with the block and sticks to it. If the velocity of the bullet is 20 m/s in the horizontal direction just before the collision then the kinetic energy just before the combined system strikes the floor, is [Take g = 10 m/s2 . Assume there is no rotational motion and loss of energy after the collision is negligible.]

(1)  23 J

(2)  21 J

(3)  20 J

(4)  19 J

Answer: (2)

11. A metallic sphere cools from 50°C to 40°C in 300 s. If atmospheric temperature around is 20°C, then the sphere’s temperature after the next 5 minutes will be close to :

(1)  35°C

(2)  31°C

(3)  33°C

(4)  28°C

Answer: (3)

12. To raise the temperature of a certain mass of gas by 50°C at a constant pressure, 160 calories of heat is required. When the same mass of gas is cooled by 100°C at constant volume, 240 calories of heat is released. How many degrees of freedom does each molecule of this gas have (assume gas to be ideal)?

(1)  6

(2)  7

(3)  5

(4)  3

Answer: (1)

13. The radius R of a nucleus of mass number A can be estimated by the formula R = (1.3 × 10–15)A 1/3 m. It follows that the mass density of a nucleus is of the order of: (M = Mneut =1.67 × 10–27 kg)

(1)  1017 kg m3

(2)  1010 kg m3

(3)  1024 kg m3

(4)  103 kg m3

Answer: (1)

14. A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field B. Then the field inside the paramagnetic substance is:

(1)  much large than and parallel to 

(2)  zero

(3)

(4)  much large than but opposite to

Answer: (2)

15. Concentric metallic hollow spheres of radii R and 4R hold charges Q1 and Q2 Given that surface charge densities of the concentric spheres are equal, the potential difference V(R) – V(4R) is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

16. The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is  The magnetic field  at the moment t = 0 is:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

17. A uniform magnetic field B exists in a direction perpendicular to the plane of a square loop made of a metal wire. The wire has a diameter of 4 mm and a total length of 30 cm. The magnetic field changes with time at a steady rate dB/dt = 0.032 Ts–1. The induced current in the loop is close to (Resistivity of the metal wire is 1.23 × 10–8 Ωm)

(1)  0.53 A

(2)  0.61 A

(3)  0.34 A

(4)  0.43 A

Answer: (2)

18. Hydrogen ion and singly ionized helium atom are accelerated, from rest, through the same potential difference. The ratio of final speeds of hydrogen and helium ions is close to:

(1)  2:1

(2)  1:2

(3)  5:7

(4)  10:7

Answer: (1)

19. Two light waves having the same wavelength λ in vacuum are in phase initially. Then the first wave travels a path L1 through a medium of refractive index n1 while the second wave travels a path of length L2 through a medium of refractive index n2. After this the phase difference between the two waves is:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

20. A calorimeter of water equivalent 20 g contains 180 g of water at 25°C. ‘m’ grams of steam at 100°C is mixed in it till the temperature of the mixture is 31°C. The value of ‘m’ is close to (Latent heat of water = 540 cal g–1, specific heat of water = 1 cal g–1 °C–1)

(1)  2

(2)  2.6

(3)  4

(4)  3.2

Answer: (1)

21. If minimum possible work is done by a refrigerator in converting 100 grams of water at 0°C to ice, how much heat (in calories) is released to the surroundings at temperature 27°C (Latent heat of ice = 80 Cal/gram) to the nearest integer?

Answer: (8791)

22. An massless equilateral triangle EFG of side ‘a’ (As shown in figure) has three particles of mass m situated at its vertices. The moment of inertia of the system about the each line EX perpendicular to EG in the plane of EFG is  where N is an integer. The value of N is _____.

Answer: (25)

23. A galvanometer coil has 500 turns and each turn has an average area of 3 × 10–4 m2. If a torque of 1.5 Nm is required to keep this coil parallel to a magnetic field when a current of 0.5 A is flowing through it, the strength of the field (in T) is ______.

Answer: (20)

24. A block starts moving up an inclined plane of inclination 30° with an initial velocity of v0. It comes back to its initial position with velocity v0/2. . The value of the coefficient of kinetic friction between the block and the inclined plane is close to 1/1000. The nearest integer to I is____.

Answer: (346)

25. When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a distance of 10 cm from the mirror. If the object is moved with a speed of 9 cms–1, the speed (in cms–1) with which image moves at that instant is ____.

Answer: (1)

Chemistry

1. The five successive ionization enthalpies of an element are 800, 2427, 3658, 25024 and 32824 kJ mol–1. The number of valence electrons in the element is:

(1)  2

(2)  4

(3)  3

(4)  5

Answer: (3)

2. The incorrect statement is:

(1)  Manganate and permanganate ions are tetrahedral

(2)  In manganate and permanganate ions, the -bonding takes place by the overlap of p orbitals of oxygen and d-orbitals of manganese

(3)  Manganate and permanganate ions are paramagnetic

(4)  Manganate ion is green in colour and permanganate ion is purple in colour

Answer: (3)

3. Match the following drugs with their therapeutic actions:

(i) Ranitidine (a) Antidepressant

(ii) Nardil (Phenelzine) (b) Antibiotic

(iii)Chloramphenicol (c) Antihistamine

(iv) Dimetane (Brompheniramine) (d) Antacid

(e) Analgesic

(1)  (i)-(d); (ii)-(a); (iii)-(b); (iv)-(c)

(2)  (i)-(d); (ii)-(c); (iii)-(a); (iv)-(e)

(3)  (i)-(a); (ii)-(c); (iii)-(b); (iv)-(e)

(4)  (i)-(e); (ii)-(a); (iii)-(c); (iv)-(d)

Answer: (1)

4. An ionic micelle is formed on the addition of

(1)  liquid diethyl ether to aqueous NaCl solution

(2)  sodium stearate to pure toluene

(3)  excess water to liquid 

(4)  excess water to liquid 

Answer: (3)

5. Among the statements (I–IV), the correct ones are:

(I) Be has a smaller atomic radius compared to Mg.

(II) Be has higher ionization enthalpy than Al.

(III) Charge/radius ratio of Be is greater than that of Al.

(IV) Both Be and Al form mainly covalent compounds.

(1)  (I), (II) and (IV)

(2)  (I), (II) and (III)

(3)  (II), (III) and (IV)

(4)  (I), (III) and (IV)

Answer: (1)

6. Complex A has a composition of H12O6Cl3 If the complex on treatment with conc. H2SO4 loses 13.5% of its original mass, the correct molecular formula of A is: [Given: the atomic mass of Cr = 52 amu and Cl = 35 amu]

(1)  [Cr(H2O)5Cl]Cl2 .H2O

(2)  [Cr(H2O)4Cl2]Cl.2H2O

(3)  [Cr(H2O)3Cl3].3H2O

(4)  [Cr(H2O)6]Cl3

Answer: (2)

7. The decreasing order of reactivity of the following compounds towards nucleophilic substitution (SN2) is:

(1)  (III) > (II) > (IV) > (I)

(2)  (IV) > (II) > (III) > (I)

(3)  (II) > (III) > (IV) > (I)

(4)  (II) > (III) > (I) > (IV)

Answer: (3)

8. The increasing order of the reactivity of the following compounds in nucleophilic addition reaction is: Propanal, Benzaldehyde, Propanone, Butanone

(1)  Benzaldehyde < Propanal < Propanone < Butanone

(2)  Propanal < Propanone < Butanone < Benzaldehyde

(3)  Butanone < Propanone < Benzaldehyde < Propanal

(4)  Benzaldehyde < Butanone < Propanone < Propanal

Answer: (3)

9. The major product in the following reaction is:

Answer: (3)

10. The incorrect statement(s) among (a) – (d) regarding acid rain is (are):

(a) It can corrode water pipes.

(b) It can damage structures made up of stone.

(c) It cannot cause respiratory ailments in animals

(d) It is not harmful for trees

(1)  (a), (b) and (d)

(2)  (a), (c) and (d)

(3)  (c) and (d)

(4)  (c) only

Answer: (3)

11. 100 mL of 0.1 M HCl is taken in a beaker and to it, 100 mL of 0.1 M NaOH is added in steps of 2 mL and the pH is continuously measured. Which of the following graphs correctly depicts the change in pH?

Answer: (3)

12. Consider the hypothetical situation where the azimuthal quantum number, l, takes values 0, 1, 2, …… n + 1, where n is the principal quantum number. Then, the element with atomic number:

(1)  13 has a half-filled valence subshell

(2)  9 is the first alkali metal

(3)  8 is the first noble gas

(4)  6 has a 2p-valence subshell

Answer: (1)

13. The d-electron configuration of [Ru(en)3]Cl2 and [Fe(H2O)6]Cl2, respectively are:

(1)  t42g e2g and t62g eog

(2)  t62g eog and t62g eog

(3)  t42g e2g and t42g e2g

(4)  t62g e0g and t42g e2g

Answer: (4)

14. Consider the following molecules and statements related to them:

(a) (B) is more likely to be crystalline than (A)

(b) (B) has a higher boiling point than (A)

(c) (B) dissolves more readily than (A) in water

Identify the correct option from below:

(1)  (a) and (c) is true

(2)  only (a) is true

(3)  (b) and (c) are true

(4)  (a) and (b) are true

Answer: (*)

15. The strengths of 5.6 volume hydrogen peroxide (of density 1 g/mL) in terms of mass percentage and molarity (M), respectively, are: (Take the molar mass of hydrogen peroxide as 34 g/mol)

(1)  0.85 and 0.5

(2)  0.85 and 0.25

(3)  1.7 and 0.25

(4)  1.7 and 0.5

Answer: (4)

16. The compound A in the following reactions is:

Answer: (1)

17. A mixture of one mole each of H2, He and O2 each are enclosed in a cylinder of volume V at temperature T. If the partial pressure of H2 is 2 atm, the total pressure of the gases in the cylinder is:

(1)  6 atm

(2)  14 atm

(3)  38 atm

(4)  22 atm

Answer: (1)

18. Three isomers A, B and C (mol. formula C8H11N) give the following results:

Answer: (2)

19. For the reaction 2A + 3B + (3 / 2) C → 3P, which statement is correct?

(1) 

(2) 

(3) 

(4) 

Answer: (3)

20. Consider the following reaction:

The product ‘P’ gives positive ceric ammonium nitrate test. This is because of the presence of which of these –OH group(s)?

(1)  (b) only

(2)  (b) and (d)

(3)  (c) and (d)

(4)  (d) only

Answer: (1)

21. The volume (in mL) of 0.1 N NaOH required to neutralise 10 mL of 0.1 N phosphinic acid is ___________.

Answer: (10 ml)

22. An acidic solution of dichromate is electrolyzed for 8 minutes using 2A current. As per the following equation

The amount of Cr3+ obtained was 0.104 g. The efficiency of the process (in %) is (Take: F = 96000 C, At. mass of chromium = 52) _______.

Answer: (60%)

23. If 250 cm3 of an aqueous solution containing 0.73 g of a protein A is isotonic with one litre of another aqueous solution containing 1.65 g of a protein B, at 298 K, the ratio of the molecular masses of A and B is ______ × 10–2 (to the nearest integer).

Answer: (177)

24. 6.023 × 1022 molecules are present in 10 g of a substance ‘x’. The molarity of a solution containing 5 g of substance ‘x’ in 2 L solution is _____ × 10–3.

Answer: (25)

25. The number of

groups present in a tripeptide Asp–Glu–Lys is ____.

Answer: (5)

Mathematics

1. If x3dy+xy dx = x2dy+2y dx; y(2) = e and x>1, then y(4) is equal to:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

2. Let A be a 3×3 matrix such that  and B = adj(adj A). If |A| = λ and |(B1)T|=μ, then the ordered pair, (|λ|, μ) is equal to:

(1)  (9, 1/81)

(2)  (9, 1/9)

(3)  (3, 1/81)

(4)  (3, 81)

Answer: (3)

3. Let a, b, c ε R be such that a2 + b2 + c2 = 1, if  where θ = π/9, then the angle between the vectors  and  is

(1)  π/2

(2)  2π/3

(3)  π/9

(4)  0

Answer: (1)

4. Suppose f(x) is a polynomial of degree four, having critical points at (−1, 0, 1). If T = {x ε R f(x) = f(0)}, then the sum of squares of all the elements of T is:

(1)  6

(2)  2

(3)  8

(4)  4

Answer: (4)

5. If the value of the integral  then k is equal to:

(1)  2√3 + π

(2)  3√2 + π

(3)  3√2 − π

(4)  2√3 − π

Answer: (4)

6. If the term independent of x in the expansion of  is k, then 18 k is equal to:

(1)  5

(2)  9

(3)  7

(4)  11

Answer: (3)

7. If a triangle ABC has vertices A(−1, 7), B(−7, 1) and C(5, −5), then its orthocentre has coordinates;

(1)  (−3, 3)

(2)  (−3/5, 3/5)

(3)  (3/5, −3/5)

(4)  (3, −3)

Answer: (1)

8. Let e1 and e2 be the eccentricities of the ellipse,  (b < 5) and the hyperbola,  respectively satisfying e1e2 = 1. If α and β are the distances between the foci of the ellipse and the foci of the hyperbola respectively, then the ordered pair (α, β) is equal to:

(1)  (8, 12)

(2)  (24/5, 10)

(3)  (20/3, 12)

(4)  (8, 10)

Answer: (4)

9. If z1, z2 are complex numbers such that Re(z1) = |z1 − 1|, Re(z2) = |z2 − 1| and arg (z1 − z2) = π/6, then Im(z1 + z2) is equal to:

(1)  2√3

(2)  2/√3

(3)  1/√3

(4)  √3/2

Answer: (1)

10. The set of all real values of λ for which the quadratic equations, (λ2 + 1) x2 − 4λx + 2 = 0 always have exactly one root in the interval (0,1) is:

(1)  (−3, −1)

(2)  (2, 4)

(3)  (1, 3)

(4)  (0, 2)

Answer: (3)

11. Let the latus rectum of the parabola y2 = 4x be the common chord to the circles C1 and C2 each of them having radius 2√5. Then, the distance between the centres of the circles C1 and C2 is:

(1)  8

(2)  8√5

(3)  4√5

(4)  12

Answer: (1)

12. The plane which bisects the line joining the points (4, −2, 3) and (2, 4, −1) at right angles also passes through the point:

(1)  (0, −1, 1)

(2)  (4, 0, 1)

(3)  (4, 0, −1)

(4)  (0, 1, −1)

Answer: (3)

13. is equal to:

(1)  (2/9)4/3

(2)  (2/3)4/3

(3)  (2/3) (2/9)1/3

(4)  (2/9) (2/3)1/3

Answer: (3)

14. Let xi (1 ≤ i ≤ 10)be ten observations of a random variable X. If  and  where 0 ≠ p ε R , then the standard deviation of these observations is :

(1)  7/10

(2)  9/10

(3) 

(4)  4/5

Answer: (2)

15. The probability that a randomly chosen 5 digit number is made from exactly two digits

(1)  134/104

(2)  121/104

(3)  135/104

(4)  150/104

Answer: (3)

16. If where C is a constant of integration, then the ordered pair (A(x), B(x)) can be:

(1)  (x + 1, −√x)

(2)  (x – 1, −√x)

(3)  (x + 1, √x)

(4)  (x – 1, √x)

Answer: (1)

17. If the sum of the series  nth term is 488 and then nth term is negative, then:

(1)  n = 60

(2)  n = 41

(3)  nth term is −4

(4)  nth term is 

Answer: (3)

18. Let p, q, r be three statements such that the truth value of (p ˄ q) → (∼q ˅ r) is F. Then the truth values of p, q, r are respectively:

(1)  F, T, F

(2)  T, F, T

(3)  T, T, F

(4)  T, T, T

Answer: (3)

19. If the surface area of a cube is increasing at a rate of 3.6 cm2/sec, retaining its shape; then the rate of change of its volume (in cm3/sec), when the length of a side of the cube is 10cm, is :

(1)  9

(2)  10

(3)  18

(4)  20

Answer: (1)

20. Let R1 and R2 be two relations defined as follows:

R1 = {(a,b) ∈ R2 : a2 + b2 ∈ Q} and

R2 = {(a,b) ∈ R2 : a2 + b2 ∉Q}, where Q is the set of all rational numbers. Then :

(1)  R1 is transitive but R2 is not transitive

(2)  R1 and R2 are both transitive

(3)  R2 is transitive but R1 is not transitive

(4)  Neither R1 nor R2 is transitive

Answer: (4)

21. If m arithmetic means (A.Ms) and three geometric means (G.Ms) are inserted between 3 and 243 such that 4th A.M. is equal to 2nd G.M., then m is equal to

Answer: (39)

22. Let a plane P contain two lines  and  If Q(α, β, γ) is the foot of the perpendicular drawn from the point M(1, 0, 1) to P, then 3(α + β + γ) equals_____

Answer: (5)

23. Let S be the set of all integer solutions, (x, y, z), of the system of equations

x – 2y + 5z = 0

−2x + 4y + z = 0

−7x + 14y + 9z = 0

such that 15 ≤ x2 + y2 + z2 ≤ 150. Then, the number of elements in the set S is equal to ______

Answer: (8)

24. The total number of 3 digit numbers, whose sum of digits is 10, is:

Answer: (54)

25. If the tangent to the curve, y = ex at a point (c, ec) and the normal to the parabola, y2 = 4x at the point (1,2) intersect at the same point on the x-axis, then the value of c is:

Answer: (4)

JEE Main September 3 2020 Shift 1 Question Paper with Answer Key

Physics

1. A block of mass m = 1 kg slides with velocity v = 6 m/s on a frictionless horizontal surface and collides with a uniform vertical rod and sticks to it as shown. The rod is pivoted about O and swings as a result of the collision making angle θ before momentarily coming to rest. If the rod has mass M = 2 kg, and length l = 1m, the value θ of is approximately: (take g = 10 m/s2)

(1)  49°

(2)  63°

(3)  69°

(4)  55°

Answer: (2)

2. A uniform thin rope of length 12 m and mass 6 kg hangs vertically from a rigid support and a block of mass 2 kg is attached to its free end. A transverse short wave train of wavelength 6 cm is produced at the lower end of the rope. What is the wavelength of the wave train (in cm) when it reaches the top of the rope?

(1)  12

(2)  3

(3)  9

(4)  6

Answer: (1)

3. When a diode is forward biased, it has a voltage drop of 0.5 V. The safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode so that the current does not exceed the safe limit is:

(1)  300 Ω

(2)  200 Ω

(3)  50 Ω

(4)  100 Ω

Answer: (4)

4. Using screw gauge of pitch 0.1 cm and 50 divisions on its circular scale, the thickness of an object is measured. It should correctly be recorded as:

(1)  2.125 cm

(2)  2.124 cm

(3)  2.123 cm

(4)  2.121 cm

Answer: (2)

5. Model a torch battery of length l to be made up of a thin cylindrical bar of radius ‘a’ and a concentric thin cylindrical shell of radius ‘b’ filled in between with an electrolyte of resistivity ρ (see figure). If the battery is connected to a resistance of value R, the maximum joule heating in R will take place for:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

6. Consider a gas of triatomic molecules. The molecules are assumed to be triangular and made of massless rigid rods whose vertices are occupied by atoms. The internal energy of a mole of the gas at temperature T is:

(1) 

(2)  3RT

(3) 

(4) 

Answer: (2)

7. An elliptical loop having resistance R, of semi major axis a, and semi minor axis b is placed in magnetic field as shown in the figure. If the loop is rotated about the x-axis with angular frequency ω, the average power loss in the loop due to Joule heating is:

(1) 

(2) 

(3) 

(4)  Zero

Answer: (3)

8. A balloon filled with helium (32° C and 1.7 atm.) bursts. Immediately afterwards the expansion of helium can be considered as:

(1)  reversible isothermal

(2)  irreversible isothermal

(3)  reversible adiabatic

(4)  irreversible adiabatic

Answer: (4)

9. When the wavelength of radiation falling on a metal is changed from 500 nm to 200 nm, the maximum kinetic energy of the photoelectrons becomes three times larger. The work function of the metal is close to:

(1)  1.02 eV

(2)  0.61 eV

(3)  0.52 eV

(4)  0.81 eV

Answer: (2)

10. Two isolated conducting spheres S1 and S2 of radius (2/3) R and (1/3) R have 12 μC and –3μC charges, respectively, and are at a large distance from each other. They are now connected by a conducting wire. A long time after this is done the charges on S1 and S2 are respectively:

(1)  6 μC and 3 μC

(2)  4.5 μC on both

(3)  + 4.5 μC and –4.5 μC

(4)  3 μC and 6 μC

Answer: (1)

11. In a radioactive material, fraction of active material remaining after time t is 9/16. The fraction that was remaining after t/2 is:

(1)  3/4

(2)  7/8

(3)  4/5

(4)  3/5

Answer: (1)

12. Moment of inertia of a cylinder of mass M, length L and radius R about an axis passing through its centre and perpendicular to the axis of the cylinder is  If such a cylinder is to be made for a given mass of a material, the ratio L /R for it to have minimum possible I is:

(1)  2/3

(2)  3/2

(3)  √2/3

(4)  √3/2

Answer: (4)

13. A satellite is moving in a low nearly circular orbit around the earth. Its radius is roughly equal to that of the earth’s radius Re. By firing rockets attached to it, its speed is instantaneously increased in the direction of its motion so that it become √3/2 times larger. Due to this the farthest distance from the centre of the earth that the satellite reaches is R. Value of R is:

(1)  2Re

(2)  3Re

(3)  4Re

(4)  2.5 Re

Answer: (2)

14. Pressure inside two soap bubbles are 1.01 and 1.02 atmosphere, respectively. The ratio of their volumes is:

(1)  4 : 1

(2)  2 : 1

(3)  0.8 : 1

(4)  8 : 1

Answer: (4)

15. In a Young’s double slit experiment, light of 500 nm is used to produce an interference pattern. When the distance between the slits is 0.05 mm, the angular width (in degree) of the fringes formed on the distance screen is close to:

(1)  0.17°

(2)  0.07°

(3)  0.57°

(4)  1.7°

Answer: (3)

16. A 750 Hz, 20 V (rms) source is connected to a resistance of 100 Ω, an inductance of 0.1803 H and a capacitance of 10 μ F all in series. The time in which the resistance (heat capacity 2 J/°C) will get heated by 10°C. (assume no loss of heat to the surroundings) is close to:

(1)  245 s

(2)  365 s

(3)  418 s

(4)  348 s

Answer: (4)

17. Magnitude of magnetic field (in SI units) at the centre of a hexagonal shape coil of side 10 cm, 50 turns and carrying current I (Ampere) in units of μ0I/π is:

(1)  250√3

(2)  50√3

(3)  500√3

(4)  5√3

Answer: (3)

18. The magnetic field of a plane electromagnetic wave is  where c = 3 × 108 ms1 is the speed of light.

The corresponding electric field is:

(1) 

(2) 

(3) 

(4) 

Answer: (1)

19. A charged particle carrying charge 1 μC is moving with velocity  If an external magnetic field of  exists in the region where the particle is moving then the force on the particle is  The vector  is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

20. In the circuit shown in the figure, the total charge is 750 μC and the voltage across capacitor C2 is 20 V. Then the charge on capacitor C2 is:

(1)  650 μC

(2)  450 μC

(3)  590 μC

(4)  160 μC

Answer: (3)

21. A person of 80 kg mass is standing on the rim of a circular platform of mass 200 kg rotating about its axis at 5 revolutions per minute (rpm). The person now starts moving towards the centre of the platform. What will be the rotational speed (in rpm) of the platform when the person reaches its centre _____?

Answer: (9)

22. An observer can see through a small hole on the side of a jar (radius 15 cm) at a point at height of 15 cm from the bottom (see figure). The hole is at a height of 45 cm. When the jar is filled with a liquid up to a height of 30 cm the same observer can see the edge at the bottom of the jar. If the refractive index of the liquid is N/100, where N is an integer, the value of N is _____.

Answer: (158)

23. A cricket ball of mass 0.15 kg is thrown vertically up by a bowling machine so that it rises to a maximum height of 20 m after leaving the machine. If the part pushing the ball applies a constant force F on the ball and moves horizontally a distance of 0.2 m while launching the ball, the value of F(in N) is (g = 10 ms–2)_____.

Answer: (150 N)

24. When a long glass capillary tube of radius 0.015 cm is dipped in a liquid, the liquid rises to a height of 15 cm within it. If the contact angle between the liquid and glass to close to 0°, the surface tension of the liquid, in milli Newton m–1 is [ρ(liquid) =900 kgm–3 , g = 10 ms–2] (Give answer in closes integer)____.

Answer: (101)

25. A bakelite beaker has volume capacity of 500 cc at 30°C. When it is partially filled with Vm volume (at 30°C) of mercury, it is found that the unfilled volume of the beaker remains constant as temperature is varied. If γ(beaker) = 6 × 10–6 °C–1 and γ(mercury)= 1.5 × 10–4 °C–1, where γ is the coefficient of volume expansion, then Vm (in cc) is close to ____.

Answer: (20)

Chemistry

1. It is true that:

(a)  A second order reaction is always a multistep reaction

(b)  A first order reaction is always a single step reaction

(c)  A zero order reaction is a multistep reaction

(d) A zero order reaction is a single step reaction

Answer: (c)

2. An acidic buffer is obtained on mixing:

(a)  100 mL of 0.1 M HCl and 200 mL of 0.1 M CH3COONa

(b)  100 mL of 0.1 M HCl and 200 mL of 0.1 M NaCl

(c)  100 mL of 0.1 M CH3 COOH and 100 mL of 0.1 M NaOH

(d) 100 mL of 0.1 M CH3COOH and 200 mL of 0.1 M NaOH

Answer: (1)

3. The Kjeldahl method of Nitrogen estimation fails for which of the following reaction products?

(a)  (a), (c) and (d)

(b)  (b) and (c)

(c)  (c) and (d)

(d) (a) and (d)

Answer: (c)

4. If the boiling point of H2O is 373 K, the boiling point of H2S will be :

(a)  greater than 300 K but less than 373 K

(b)  equal to 373 K

(c)  more than 373 K

(d) less than 300 K

Answer: (d)

5. The complex that can show optical activity is :

(a)  cis– [CrCl2 (ox)2]3− (ox – oxalate)

(b)  trans – [Fe (NH3)2 (CN)4]

(c)  trans – [Cr (Cl2) (ox)2]3−

(d) cis– [Fe (NH3)2 (CN)4]−

Answer: (a)

6. Which one of the following compounds possesses the most acidic hydrogen?

Answer: (c)

7. Aqua regia is used for dissolving noble metals (Au, Pt, etc.). The gas evolved in this process is :

(a)  N2O3

(b)  N2

(c)  N2O5

(d) NO

Answer: (d)

8. The antifertility drug “Novestrol” can react with:

(a)  Br2 / water; ZnCl2 / HCl; FeCl3

(b)  Br2 / water; ZnCl2 / HCl; NaOCl

(c)  Alcoholic HCN; NaOCl; ZnCl2 / HCl

(d) ZnCl2 / HCl; FeCl3; Alcoholic HCN

Answer: (a)

9. Which of the following compounds produces an optically inactive compound on hydrogenation?

Answer: (c)

10. Of the species, NO, NO+, NO2+ and NO, the one with minimum bond strength is:

(a)  NO

(b)  NO+

(c)  NO2+

(d) NO

Answer: (a)

11. Glycerol is separated in soap industries by:

(a)  Fractional distillation

(b)  Distillation under reduced pressure

(c)  Differential extraction

(d) Steam distillation

Answer: (b)

12. Thermal power plants can lead to:

(a)  Ozone layer depletion

(b)  Blue baby syndrome

(c)  Eutrophication

(d) Acid rain

Answer: (d)

13. Henry’s constant (in kbar) for four gases ɑ, β, 𝛾, δ and δ in water at 298 K is given below:

α β γ δ
KH 50 2 2 × 10−5 0.5

(density of water = 103 kg m3 at 298 K)

This stable implies that :

(a)  solubility of γ at 308 K is lower than at 298 K

(b)  The pressure of a 55.5 molal solution of δ is 250 bar

(c)  α has the highest solubility in water at a given pressure

(d) The pressure of a 55.5 molal solution of γ is 1 bar

Answer: (a)

14. The electronic spectrum of [Ti(H2O)6]3+ shows a single broad peak with a maximum at 20,300 cm-1. The crystal field stabilization energy (CFSE) of the complex ion, in kJ mol−1, is:

(1 kJ mol−1 = 83.7 cm−1)

(a)  83.7

(b)  242.5

(c)  145.5

(d) 97

Answer: (d)

15. The atomic number of the element unnilennium is:

(a)  109

(b)  102

(c)  119

(d) 108

Answer: (1)

16. An organic compound [A], molecular formula C10H20O2 was hydrolyzed with dilute sulphuric acid to give a carboxylic acid [B] and an alcohol [C]. Oxidation of [C] with CrO3−H2SO4 produced [B]. Which of the following structures are not possible for [A]?

Answer: (b)

17. The mechanism of SN1 reaction is given as:

A student writes general characteristics based on the given mechanism as:

(1) The reaction is favoured by weak nucleophiles.

(2) RΘ would be easily formed if the substituents are bulky.

(3) The reaction is accompanied by racemization.

(4) The reaction is favoured by non-polar solvents. Which observations are correct?

(a)  (1) and (2)

(b)  (1), (2) and (3)

(c)  (1) and (3)

(d) (2) and (4)

Answer: (b)

18. Tyndall effect is observed when:

(a)  The diameter of dispersed particles is much smaller than the wavelength of light used.

(b)  The diameter of dispersed particles is much larger than the wavelength of light used.

(c)  The refractive index of the dispersed phase is greater than that of the dispersion medium.

(d) The diameter of dispersed particles is similar to the wavelength of light used.

Answer: (d)

19. Let CNaCl and CBaSO4 be the conductances (in S) measured for saturated aqueous solutions of NaCl and BaSO4, respectively, at a temperature T. Which of the following is false?

(a)  CNaCl (T2) > CBaSo4 (T1) for T2 > T1

(b)  CBaSo4 (T2) > CNaCl (T1) for T2 > T1

(c)  Ionic mobilities of ions from both salts increase with T.

(d) CNaCl >> CBaSo4 at a given T

Answer: (d)

20. In a molecule of pyrophosphoric acid, the number of P−OH, P = O and P − O − P bonds / moiety(ies) respectively are:

(a)  3, 3 and 3

(b)  4, 2 and 1

(c)  2, 4 and 1

(d) 4, 2 and 0

Answer: (b)

21. The mole fraction of glucose (C6H12O6) in an aqueous binary solution is 0.1. The mass percentage of water in it, to the nearest integer, is _______.

Answer: (47%)

22. The volume strength of 8.9 M H2O2 solution calculated at 273 K and 1 atm is ______. (R = 0.0821 L atm K1 mol1) (rounded off to the nearest integer)

Answer: (100)

23. An element with molar mass 2.7 10−2 kg mol−1 forms a cubic unit cell with edge length 405 pm. If its density is 2.7 103 kg m−3, the radius of the element is approximately ______ 10−12 m (to the nearest integer).

Answer: (143)

24. The total number of monohalogenated organic products in the following (including stereoisomers) reaction is ______.

Answer: (8)

25. The photoelectric current from Na (Work function, w0 = 2.3 eV) is stopped by the output voltage of the cell Pt(s) H2 (g, 1 Bar) HCl (aq. pH =1) AgCl s Ag(s). The pH of aq. HCl required to stop the photoelectric current form K(w0 = 2.25 eV), all other conditions remaining the same, is _______ 102 (to the nearest integer). Given, 

Answer: (58)

Mathematics

1. The value of (2.1P02P1+4.3P2….. up to 51th term) +(1!-2!+3!-…… up to 51th term) is equal to:

(1)  1 – 51(51)!

(2)  1 + (52)!

(3)  1

(4)  1 5 (51)!

Answer: (2)

2. Let P be a point on the parabola, y2 = 12x and N be the foot of the perpendicular drawn from P on the axis of the parabola. A line is now drawn through the mid-point M of PN, parallel to its axis which meets the parabola at Q. If the y-intercept of the line NQ is 4/3 , then:

(1)  PN = 4

(2)  MQ = 1/3

(3)  PN = 3

(4)  MQ = 1/4

Answer: (4)

3. If = AX3 + BX2 + Cx + D, then B + C is equal to:

(1)  1

(2)  −1

(3)  −3

(4)  9

Answer: (3)

4. The foot of the perpendicular drawn from the point (4,2,3) to the line joining the points (1,2,3) and (1,1,0) lies on the plane:

(1)  x – y – 2z = 1

(2)  x – 2y + z = 1

(3)  2x + y – z = 1

(4)  x + 2y – z = 1

Answer: (3)

5. If y2 + loge(cos2x) = y, x∈(−π/2, π/2), then

(1)  |y´(0)|+|y´´(0)| = 1

(2)  |y´´(0)| = 0

(3)  |y´(0)|+|y´´(0)| = 3

(4)  |y´´(0)| = 2

Answer: (4)

6. is equal to:

(1)  5π/4

(2)  3π/2

(3)  7π/4

(4)  π/2

Answer: (2)

7. A hyperbola having the transverse axis of length √2 has the same foci as that of the ellipse 3x2 + 4y2 = 12, then this hyperbola does not pass through which of the following points ?

(1) 

(2) 

(3) 

(4) 

Answer: (1)

8. For the frequency distribution

Variant (X): x1 x2 x3…x15

Frequency (f): f1 f2 f3…f15

where 0 < x1 < x2 < x3 <… x15 ≤ 10 and  the standard deviation cannot be:

(1)  1

(2)  4

(3)  6

(4)  2

Answer: (3)

9. A die is thrown two times and the sum of the scores appearing on the die is observed to be a multiple of 4. Then the conditional probability that the score 4 has appeared atleast once is:

(1)  1/3

(2)  1/4

(3)  1/8

(4)  1/9

Answer: (4)

10. If the number of integral terms in the expansion of (31/2 +51/8)n is exactly 33, then the least value of n is:

(1)  128

(2)  248

(3)  256

(4)  264

Answer: (3)

11. 

(1)  π2

(2)  π2/2

(3)  √2π2

(4)  2π2

Answer: (1)

12. Consider the two sets:

A = {m ∈ R : both the roots of x2 − (m + 1) x + m + 4 = 0 are real} and B = [−3, 5).

Which of the following is not true ?

(1)  A-B = (−∞,−3) ∪ (5, ∞)

(2)  A ∩ B = {−3}

(3)  B-A = (−3, 5)

(4)  A U B = R

Answer: (1)

13. The proposition p − > ∼ (p ˄ q) is equivalent to:

(1)  (∼p) ˅(∼ q)

(2)  (∼ p) ˄q

(3)  q

(4)  (∼ p) ˅q

Answer: (4)

14. The function, f(x) = (3x − 7)x2/3, x ∈ R is increasing for all x lying in:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

15. If the first term of an A.P. is 3 and the sum of its first 25 terms is equal to the sum of its next 15 terms, then the common difference of this A.P. is:

(1)  1/6

(2)  1/5

(3)  1/4

(4)  1/7

Answer: (1)

16. The solution curve of the differential equation,  which passes through the point (0, 1), is:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

17. The area (in sq. units) of the region  is

(1)  23/16

(2)  79/16

(3)  23/6

(4)  79/24

Answer: (4)

18. If α and β are the roots of the equation x2 + px + 2 = 0 and 1/α and 1/β are the roots of the equation 2x2 + 2qx + 1 = 0, then is  equal to:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

19. The lines  and  

(1)  do not intersect for any values of l and m

(2)  intersect when l = 1 and m = 2

(3)  intersect when l = 2 and m = 1/2

(4)  intersect for all values of l and m

Answer: (1)

20. Let [t] denote the greatest integer ≤t. If for some λ ∈ R −{0, 1},  then L is equal to:

(1)  0

(2)  2

(3)  1/2

(4)  1

Answer: (2)

21. If  then the value of k is …….

Answer: (8)

22. The diameter of the circle, whose centre lies on the line x + y = 2 in the first quadrant and which touches both the lines x = 3 and y = 2, is ……

Answer: (3)

23. The value of  is equal to………..

Answer: (4)

24. Let  and A4[aij]. If a11 = 109, then a22 is equal to…………….

Answer: (10)

25. If  (m, n ∈ N) then the greatest common divisor of the least values of m and n is……………..

Answer: (4)

JEE Main September 2 2020 Shift 2 Question Paper with Answer Key

Physics

1. If momentum (P), area (A) and time (T) are taken to be the fundamental quantities then the dimensional formula for energy is:

(1)  [P1/2 AT–1]

(2)  [PA1/2 T–1]

(3)  [PA1/2 T–1]

(4)  [P2 AT–2]

Answer: (2)

2. Two uniform circular discs are rotating independently in the same direction around their common axis passing through their centres. The moment of inertia and angular velocity of the first disc are 0.1 kg –m2 and 10 rad s–1 respectively while those for the second one are 0.2 kg–m2 and 5 rad s–1 At some instant they get stuck together and start rotating as a single system about their common axis with some angular speed. The Kinetic energy of the combined system is:

(1)  2/3 J

(2)  10/3 J

(3)  5/3 J

(4)  20/3 J

Answer: (4)

3. A particle is moving 5 times as fast as an electron. The ratio of the de-Broglie wavelength of the particle to that of the electron is 1.878 × 10–4. The mass of the particle is close to:

(1)  4.8 × 10–27 kg

(2)  9.1 × 10–31 kg

(3)  9.7 × 10–28 kg

(4)  1.2 × 10–28 kg

Answer: (3)

4. A potentiometer wire PQ of 1 m length is connected to a standard cell E1. Another cell E2 of emf 1.02 V is connected with a resistance ‘r’ and switch S (as shown in figure). With switch S open, the null position is obtained at a distance of 49 cm from Q. The potential gradient in the potentiometer wire is:

(1)  0.03 V/cm

(2)  0.02 V/cm

(3)  0.04 V/cm

(4)  0.01 V/cm

Answer: (2)

5. In the following digital circuit, what will be the output at ‘Z’, when the input (A,B) are (1,0), (0,0), (1,1), (0,1):

(1)  0, 1, 0, 0

(2)  1, 1, 0, 1

(3)  0, 0, 1, 0

(4)  1, 0, 1, 1

Answer: (3)

6. A wire carrying current I is bent in the shape ABCDEFA as shown, where rectangle ABCDA and ADEFA are perpendicular to each other. If the sides of the rectangles are of lengths a and b, then the magnitude and direction of magnetic moment of the loop ABCDEFA is:

(1) 

(2) 

(3) 

(4) 

Answer: (3)

7. A small point mass carrying some positive charge on it, is released from the edge of a table. There is a uniform electric field in this region in the horizontal direction. Which of the following options then correctly describe the trajectory of the mass? (Curves are drawn schematically and are not to scale).

Answer: (3)

8. In a plane electromagnetic wave, the directions of electric field and magnetic field are represented by  What is the unit vector along direction of propagation of the wave.

(1) 

(2) 

(3) 

(4) 

Answer: (1)

9. An inductance coil has a reactance of 100 Ω. When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by 45°. The self-inductance of the coil is:

(1)  6.7 × 10–7 H

(2)  5.5 × 10–5 H

(3)  1.1 × 10–1 H

(4)  1.1 × 10–2 H

Answer: (4)

10. This displacement time graph of a particle executing S.H.M. is given in figure : (sketch is schematic and not to scale)

Which of the following statements is/are true for this motion?

(A) The force is zero at t = 3T/4

(B) The acceleration is maximum at t=T

(C) The speed is maximum at t = T/4

(D) The P.E. is equal to K.E. of the oscillation at t = T/2

(1)  (B), (C) and (D)

(2)  (A), (B) and (D)

(3)  (A) and (D)

(4)  (A), (B) and (C)

Answer: (4)

11. In a Young’s double slit experiment, 16 fringes are observed in a certain segment of the screen when light of wavelength 700 nm is used. If the wavelength of light is changed to 400 nm, the number of fringes observed in the same segment of the screen would be:

(1)  28

(2)  24

(3)  30

(4)  18

Answer: (1)

12. A heat engine is involved with exchange of heat of 1915 J, –40J, + 125J and –QJ, during one cycle achieving an efficiency of 50.0%. The value of Q is:

(1)  980 J

(2)  640 J

(3)  40 J

(4)  400 J

Answer: (1)

13. In a hydrogen atom the electron makes a transition from (n + 1)th level to the nth level. If n>>1, the frequency of radiation emitted is proportional to:

(1)  1/n2

(2)  1/n

(3)  1/n3

(4)  1/n4

Answer: (3)

14. When the temperature of a metal wire is increased from 0°C to 10°C, its length increases by 0.02%. The percentage change in its mass density will be closest to:

(1)  0.06

(2)  0.008

(3)  2.3

(4)  0.8

Answer: (1)

15. A charge Q is distributed over two concentric conducting thin spherical shells radii r and R (R > r). If the surface charge densities on the two shells are equal, the electric potential at the common centre is:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

16. A 10 μF capacitor is fully charged to a potential difference of 50V. After removing the source voltage it is connected to an uncharged capacitor in parallel. Now the potential difference across them becomes 20 V. The capacitance of the second capacitor is:

(1)  15 μF

(2)  20 μF

(3)  10 μF

(4)  30 μF

Answer: (1)

17. An ideal gas in a closed container is slowly heated. As its temperature increases, which of the following statements are true?

(A) the mean free path of the molecules decreases.

(B) the mean collision time between the molecules decreases.

(C) the mean free path remains unchanged.

(D) the mean collision time remains unchanged.

(1)  (B) and (C)

(2)  (A) and (B)

(3)  (C) and (D)

(4)  (A) and (D)

Answer: (1)

18. A capillary tube made of glass of radius 0.15 mm is dipped vertically in a beaker filled with methylene iodide (surface tension = 0.05 Nm–1, density = 667 kg m–3) which rises to height h in the tube. It is observed that the two tangents drawn from liquid-glass interfaces (from opp. sides of the capillary) make an angle of 60° with one another. Then h is close to (g=10 ms–2).

(1)  0.172 m

(2)  0.049 m

(3)  0.087 m

(4)  0.137 m

Answer: (3)

19. The height ‘h’ at which the weight of a body will be the same as that at the same depth ‘h’ from the surface of the earth is (Radius of the earth is R and effect of the rotation of the earth is neglected):

(1) 

(2) 

(3) 

(4)  R/2

Answer: (3)

20. The figure shows a region of length ‘l’ with a uniform magnetic field of 0.3 T in it and a proton entering the region with velocity 4 ×105 ms–1 making an angle 60° with the field. If the proton completes 10 revolution by the time it cross the region shown, ‘l’ is close to (mass of proton = 1.67 × 10–27 kg, charge of the proton = 1.6 × 10–19 C)

(1)  0.11 m

(2)  0.22 m

(3)  0.44 m

(4)  0.88 m

Answer: (3)

21. A light ray enters a solid glass sphere of refractive index μ= √3 at an angle of incidence 60°. The ray is both reflected and refracted at the farther surface of the sphere. The angle (in degrees) between the reflected and refracted rays at this surface is ________.

Answer: (90)

22. An ideal cell of emf 10 V is connected in circuit shown in figure. Each resistance is 2Ω. The potential difference (in V) across the capacitor when it is fully charged is _______.

Answer: (8)

23. A square shaped hole of side l =a/2 is carved out at a distance d = a/2 from the centre ‘O’ of a uniform circular disk of radius a. If the distance of the centre of mass of the remaining portion from O is –a/X, value of X (to the nearest integer) is _________.

Answer: (23)

24. A particle of mass m is moving along the x-axis with initial velocity  It collides elastically with a particle of mass 10 m at rest and then moves with half its initial kinetic energy (see figure). If sinθ1 = √n sin θ2 then value of n is

Answer: (10)

25. A wire of density 9 × 10–3 kg cm–3 is stretched between two clamps 1 m apart. The resulting strain in the wire is 4.9 × 10–4. The lowest frequency of the transverse vibrations in the wire is (Young’s modulus of wire Y = 9 ×1010 Nm–2), (to the nearest integer), _______.

Answer: (35)

Chemistry

1. Cast iron is used for the manufacture of :

(1)  Wrought iron and steel

(2)  Wrought iron and pig iron

(3)  Wrought iron, pig iron and steel

(4)  Pig iron, scrap iron and steel

Answer: (1)

2. The shape/structure of [XeF5] and XeO3F2, respectively, are :

(1)  Pentagonal planar and trigonal bipyramidal

(2)  Trigonal bipyramidal and trigonal bipyramidal

(3)  Octahedral and square pyramidal

(4)  Trigonal bipyramidal and pentagonal planar

Answer: (1)

3. Simplified absorption spectra of three complexes ((i), (ii) and (iii)) of Mn+ ion are provided below; their λmax values are marked as A, B and C respectively. The correct match between the complexes and their λmax values is :

(i) [M(NCS)6](–6+n)

(ii) [MF6](–6+n)

(iii) [M(NH3)6]n+

(1)  A-(i), B-(ii), C-(iii)

(2)  A-(iii), B-(i), C-(ii)

(3)  A-(ii), B-(iii), C-(i)

(4)  A-(ii), B-(i), C-(iii)

Answer: (2)

4. The correct observation in the following reactions is:

(1)  Formation of red colour

(2)  Formation of blue colour

(3)  Formation of violet colour

(4)  Gives no colour

Answer: (1)

5. The results given in the below table were obtained during kinetic studies of the following reaction: 2A + B → C + D

Experiment [A]/

molL1

[B]/

molL1

Initial rate/

molL1 min1

I 0.1 0.1 6.00×103
II 0.1 0.2 2.40 × 102
III 0.2 0.1 1.20 × 102
IV X 0.2 7.20 × 102
V 0.3 Y 2.88 × 101

X and Y in the given table are respectively:

(1)  0.4, 0.4

(2)  0.3, 0.4

(3)  0.4,0.3

(4)  0.3, 0.3

Answer: (2)

6. Match the type of interaction in column A with the distance dependence of their interaction energy in column B:

A                                          B

(I) ion-ion                          (a) 1/r

(II) dipole-dipole              (b) 1/r2

(III) London dispersion    (c) 1/r3

                                        (d) 1/r6

(1)  (I)-(a), (II)-(b), (III)-(d)

(2)  (I)-(a), (II)-(b), (III)-(c)

(3)  (I)-(b), (II)-(d), (III)-(c)

(4)  (I)-(a), (II)-(c), (III)-(d)

Answer: (4)

7. The major product obtained from E2 – elimination of 3-bromo-2-fluoropentane is:

Answer: (1)

8. Consider the reaction sequence given below:

Which of the following statements is true:

(1)  Changing the concentration of the base will have no effect on reaction (1)

(2)  Doubling the concentration of base will double the rate of both the reactions.

(3)  Changing the base from OH to OR will have no effect on reaction (2)

(4)  Changing the concentration of the base will have no effect on reaction (2)

Answer: (1)

9. The size of a raw mango shrinks to a much smaller size when kept in a concentrated salt solution. Which one of the following processes can explain this?

(1)  Diffusion

(2)  Osmosis

(3)  Reverse osmosis

(4)  Dialysis

Answer: (2)

10. If you spill a chemical toilet cleaning liquid on your hand, your first aid would be :

(1)  Aqueous NH3

(2)  Aqueous NaHCO­3

(3)  Aqueous NaOH

(4)  Vinegar

Answer: (2)

11. Arrange the following labelled hydrogens in decreasing order of acidity:

(1)  b > a > c > d

(2)  b > c > d > a

(3)  c > b > d > a

(4)  c > b > a > d

Answer: (2)

12. An organic compound ‘A’ (C9H10O) when treated with conc. HI undergoes cleavage to yield compounds ‘B’ and ‘C’. ‘B’ gives a yellow precipitate with AgNO3 whereas ‘C’ tautomerizes to ‘D’. ‘D’ gives a positive iodoform test. ‘A’ could be:

Answer: (1)

13. Two elements A and B have similar chemical properties. They don’t form solid hydrogen carbonates but react with nitrogen to form nitrides. A and B, respectively, are :

(1)  Na and Ca

(2)  Cs and Ba

(3)  Na and Rb

(4)  Li and Mg

Answer: (4)

14. The number of subshells associated with n = 4 and m = –2 quantum numbers is :

(1)  4

(2)  8

(3)  2

(4)  16

Answer: (3)

15. The major product of the following reaction is:

Answer: (3)

16. Two compounds A and B with the same molecular formula (C3H6O) undergo Grignard’s reaction with methylmagnesium bromide to give products C and D. Products C and D show the following chemical tests.

Test C D
Ceric ammonium nitrate test Positive Positive
Lucas Test Turbidity obtained after five minutes Turbidity obtained immediately
Iodoform Test Positive Negative

C and D respectively are:

Answer: (2)

17. Three elements X, Y and Z are in the 3rd period of the periodic table. The oxides of X, Y and Z, respectively, are basic, amphoteric and acidic, The correct order of the atomic numbers of X, Y and Z is:

(1)  X < Y < Z

(2)  Y < X < Z

(3)  Z < Y < X

(4)  X < Z < Y

Answer: (1)

18. The one that is not expected to show isomerism is:

(1)  [Ni(NH3)4 (H2O)2]2+

(2)  [Ni(en)3]2+

(3)  [Pt(NH3)2Cl2]

(4)  [Ni(NH3)2Cl2]

Answer: (4)

19. Amongst the following statements regarding adsorption, those that are valid are:

(a) ΔH becomes less negative as adsorption proceeds.

(b) On a given adsorbent, ammonia is adsorbed more than nitrogen gas.

(c) On adsorption, the residual force acting along the surface of the adsorbent increases.

(d) With an increase in temperature, the equilibrium concentration of adsorbate increases.

(1)  (b) and (c)

(2)  (c) and (d)

(3)  (a) and (b)

(4)  (d) and (a)

Answer: (3)

20. The molecular geometry of SF6 is octahedral. What is the geometry of SF4 (including lone pair(s) of electrons, if any)?

(1)  Pyramidal

(2)  Trigonal bipyramidal

(3)  Tetrahedral

(4)  Square planar

Answer: (2)

21. The ratio of the mass percentages of ‘C & H’ and ‘C & O’ of a saturated acyclic organic compound ‘X’ are 4:1 and 3:4 respectively. Then, the moles of oxygen gas required for complete combustion of two moles of organic compound ‘X’ is ___________.

Answer: (5)

22. For the disproportionation reaction 2Cu+(aq) ⇌ Cu(s) + Cu2+(aq) at K, ln K (where K is the equilibrium constant) is ________ × 10–1.

Given:

Answer: (144)

23. The work function of sodium metal is 4.41 × 10–19 If photons of wavelength 300 nm are incident on the metal, the kinetic energy of the ejected electrons will be (h = 6.63 × 10–34 J s; c = 3 × 108 m/s) __________ × 10–21 J.

Answer: (222)

24. The oxidation states of transition metal atoms in K2Cr2O7, KMnO4 and K2FeO4, respectively, are x, y and z. The sum of x, y and z is ________.

Answer: (19)

25. The heat of combustion of ethanol into carbon dioxide and water is –327 kcal at constant pressure. The heat evolved (in cal) at constant volume and 27ºC (if all gases behave ideally) is (R = 2 cal mol–1K–1) __________.

Answer: (326400)

Mathematics

1. Let f : R → R be a function which satisfies f(x + y) = f(x) + f(y) ∀ x, y ∈ if f(1) = 2 and  then the value of n, for which g(n) = 20, is:

(1)  9

(2)  5

(3)  4

(4)  20

Answer: (2)

2. If the sum of first 11 terms of an A.P, a1,a2,a3… is 0 (a1 ≠ 0) then the sum of the A.P, a1, a3, a5…a23 is ka1, where k is equal to

(1)  −121/10

(2)  −72/5

(3)  72/5

(4)  121/10

Answer: (b)

3. Let EC denote the complement of an event E. Let E1, E2 and E3 be any pair wise independent events with P(E1) > 0 and P(E1 ∩ E2 ∩ E3) = 0. Then P(E2C ∩ E3C/E1) is equal to:

(1)  P(E3C) – P(E2C)

(2)  P(E3) – P(E2C)

(3)  P(E3C) – P(E2)

(4)  P(E2C) + P(E3)

Answer: (c)

4. If the equation cos4θ+sin4θ+λ = 0 has real solutions for θ, then λ lies in the interval:

(1)  (−1/2, −1/4]

(2)  [−1, −1/2]

(3)  [−3/2, −5/4]

(4)  (−5/4, −1)

Answer: (2)

5. The area (in sq. units) of an equilateral triangle inscribed in the parabola y2 = 8x, with one of its vertices on the vertex of this parabola, is:

(1)  128√3

(2)  192√3

(3)  64√3

(4)  256√3

Answer: (2)

6. The imaginary part of  can be:

(1)  √6

(2)  −2√6

(3)  6

(4)  −√6

Answer: (2)

7. A plane passing through the point (3,1,1) contains two lines whose direction ratios are (1, −2, 2) and (2, 3, -1) respectively. If this plane also passes through the point (α, −3, 5), then α is equal to:

(1)  −5

(2)  10

(3)  5

(4)  −10

Answer: (3)

8. Let A = {X = (x, y, z)T : PX = 0 and x2 + y2 + z2}, where  then the set A:

(1)  contains more than two elements

(2)  is a singleton.

(3)  contains exactly two elements

(4)  is an empty set.

Answer: (3)

9. The equation of the normal to the curve y = (1+x)2y +cos2(sin1x) at x = 0 is:

(1)  y + 4x = 2

(2)  2y + x = 4

(3)  x + 4y = 8

(4)  y = 4x + 2

Answer: (3)

10. Consider a region R = {(x, y) ∈ R2 : x2 ≤ y ≤ 2x}. If a line y = α divides the area of region R into two equal parts, then which of the following is true.?

(1)  α3 − 6α2 + 16 = 0

(2)  3α2 − 8α3/2 + 8 = 0

(3)  α3− 6α3/2 − 16 = 0

(4)  3α2 − 8α + 8 = 0

Answer: (2)

11. Let f: (−1, ∞) → R be defined by f(0) = 1 and  x ≠ 0. Then the function f:

(1)  increases in (−1, ∞)

(2)  decreases in (−1,0) and increases in (0, ∞)

(3)  increases in (−1,0) and decreases in (0, ∞)

(4)  decreases in (−1, ∞)

Answer: (d)

12. Which of the following is a tautology?

(1)  (p→q) ˄( q→p)

(2)  (~p) ˄(p ˅q)→q

(3)  (q→p) ˅~(p→q)

(4)  (~q)˅( p˄q)→q

Answer: (2)

13. Let f(x) be a quadratic polynomial such that f(−1) + f(2) = 0. If one of the roots of f(x) = 0 is 3, then its other roots lies in:

(1)  (0, 1)

(2)  (1, 3)

(3)  (−1, 0)

(4)  (−3, −1)

Answer: (3)

14. Let S be the sum of the first 9 terms of the series:

{x + ka} + {x2 + (k + 2) a} + {x3 + (k + 4) a} + {x4 + (k + 6)a} +… where a ≠ 0 and a ≠ 1.

If  then k is equal to:

(1)  3

(2)  −3

(3)  1

(4)  −5

Answer: (2)

15. The set of all possible values of θ in the interval (0, π) for which the points (1, 2) and (sin θ, cos θ ) lie on the same side of the line x + y = 1 is:

(1)  (0, π/4)

(2)  (0, π/2)

(3)  (0, 3π/4)

(4)  (π/4, 3π/4)

Answer: (2)

16. Let n > 2 be an integer. Suppose that there are n metro stations in a city located along a circular path. Each pair of stations is connected by a straight track only. Further, each pair of nearest stations is connected by blue line, whereas all remaining pairs of stations are connected by red line. If the number of red lines is 99 times the number of blue lines, then the value of n is:

(1)  201

(2)  199

(3)  101

(4)  200

Answer: (a)

17. If a curve y = f(x), passing through the point (1, 2) is the solution of the differential equation, 2x2dy = (2xy + y2)dx, then f(1/2) is equal to:

(1) 

(2)  1 + loge 2

(3) 

(4) 

Answer: (3)

18. For some θ ∈ (0, π/2) , if the eccentricity of the hyperbola, x2 − y2sec2θ = 10 is √5 times the eccentricity of the ellipse, x2sec2θ + y2 = 5, then the length of the latus rectum of the ellipse, is:

(1)  4√5/3

(2)  2√5/3

(3)  2√6

(4)  √30

Answer: ()

19. is equal to :

(1)  e

(2)  e2

(3)  2

(4)  1

Answer: (2)

20. Let a, b, c ∈ R be all non-zero and satisfy a3 + b3 + c3 = 2. If the matrix satisfies  ATA = I, then a value of abc can be:

(1)  2/3

(2)  3

(3)  −1/3

(4)  1/3

Answer: (d)

21. Let the position vectors of points ‘A’ and ‘B’ be  and   A point ‘P’ divides the line segment AB internally in the ratio λ : 1 (λ > 0). If O is the origin and then λ is equal to_______

Answer: (0.8)

22. Let [t] denote the greatest integer less than or equal to t. Then the value of  is :

Answer: (1)

23. If  then (dy/dx) at x = 0 is:

Answer: (91)

24. If the variance of the terms in an increasing A.P. b1, b2, b3, …., b11 is 90, then the common difference of this A.P. is

Answer: (3)

25. For a positive integer n, (1+1/x)n is expanded in increasing powers of x. If three consecutive coefficients in this expansion are in the ratio, 2:5:12, then n is equal to

Answer: (118)

JEE Main September 2 2020 Shift 1 Question Paper with Answer Key

Physics

1. The mass density of a spherical galaxy K varies as K/r over a large distance ‘r’ from its centre. In that region, a small star is in a circular orbit of radius R. Then the period of revolution, T depends on R as:

(a)  T2 ∝ R

(b)  T2 ∝ R3

(c)  T2 ∝ (1/R3)

(d) T ∝ R

Answer: (a)

2. An amplitude modulated wave is represented by the expression vm= 5(1 + 0.6 cos 6280 t )sin (211 × 104t) volts. The minimum and maximum amplitudes of the amplitude modulated wave are, respectively :

(a) 

(b)  5V, 8V

(c)  3V, 5V

(d) 

Answer: (d)

3. A spherical mirror is obtained as shown in the figure from a hollow glass sphere. If an object is positioned in front of the mirror, what will be the nature and magnification of the image of the object ? (Figure drawn as schematic and not to scale)

(a)  Erect, virtual and unmagnified

(b)  Inverted, real and magnified

(c)  Erect, virtual and magnified

(d) Inverted, real and unmagnified

Answer: (d)

4. A cylindrical vessel containing a liquid is rotated about its axis so that the liquid rises at its sides as shown in the figure. The radius of vessel is 5 cm an and the angular speed of rotation is ω rad s1. The difference in the height, h (in cm) of liquid at the centre of vessel and at the side will be:

(a)  5ω2/2g

(b)  2ω2/25g

(c)  25ω2/2g

(d) 2ω2/5g

Answer: (c)

5. If speed V, area A and force F are chosen as fundamental units, then the dimension of;

Young’s modulus will be

(a)  FA2V3

(b)  FA2V2

(c)  FA1V0

(d) FA2V1

Answer: (c)

6. A bead of mass m stays at point P (a, b) on a wire bent in the shape of a parabola y = 4Cx2 and rotating with angular speed ω (see figure). The value of ω is (neglect friction):

(a) 

(b)  2√gC

(c) 

(d) 2√2gC

Answer: (d)

7. Magnetic materials used for making permanent magnets (P) and magnets in a transformer (T) have different properties of the following, which property best matches for the type of magnet required?

(a)  P : Small retentivity, large coercivity

(b)  P : Large retentivity, large coercivity

(c)  T : Large retentivity, large coercivity

(d) T : Large retentivity, small coercivity

Answer: (b)

8. Interference fringes are observed on a screen by illuminating two thin slits 1 mm apart with a light source (λ = 632.8 nm). The distance between the screen and the slits is 100cm. If a bright fringe is observed on screen at a distance of 1.27 mm from the central bright fringe, then the path difference between the waves, which are reaching this point from the slits is close to:

(a)  2.05 μm

(b)  2.87 nm

(c)  2 nm

(d) 1.27 μm

Answer: (d)

9. A gas mixture consists of 3 moles of oxygen and 5 moles of argon at temperature T. Assuming the gases to be ideal and the oxygen bond to be rigid, the total internal energy (in units of RT) of the mixture is:

(a)  11

(b)  13

(c)  15

(d) 20

Answer: (c)

10. A plane electromagnetic wave, has frequency of 2.0 × 1010 Hz and its energy density is 1.02 × 10–8 J/m3 in vacuum. The amplitude of the magnetic field of the wave is close

(a)  160 nT

(b)  150 nT

(c)  180 nT

(d) 190 nT

Answer: (a)

11. Consider four conducting materials copper, tungsten, mercury and aluminium with resistivity ρc, ρm, ρT and ρA Then:

(a)  ρc > ρA > ρT

(b)  ρA> ρm > ρc

(c)  ρA> ρT > ρc

(d) ρm > ρA> ρc

Answer: (d)

12. A beam of protons with speed 4 × 105 ms–1 enters a uniform magnetic field of 0.3 T at an angle of 60° to the magnetic field. The pitch of the resulting helical path of protons is close to: (Mass of the proton =1.67 × 10–27 kg, charge of the proton =1.69 × 10–19C)

(a)  4 cm

(b)  2 cm

(c)  12 cm

(d) 5 cm

Answer: (a)

13. Two identical strings X and Z made of same material have tension Tx and Tz in them. If their fundamental frequencies are 450 Hz and 300 Hz, respectively, then the ratio Tx/Tz is:

(a)  2.25

(b)  1.25

(c)  0.44

(d) 1.5

Answer: (a)

14. A uniform cylinder of mass M and radius R is to be pulled over a step of height a(a < R) by applying a force F at its centre ‘O’ perpendicular to the plane through the axes of the cylinder on the edge of the step (see figure). The minimum value of F required is

(a) 

(b) 

(c) 

(d) 

Answer: (d)

15. In a reactor, 2 kg of 92U235 fuel is fully used up in 30 days. The energy released perfission is 200 MeV. Given that the Avogadro number, N = 6.023 × 1026 per kilo mole and1 eV =1.6 × 10–19 The power output of the reactor is close to

(a)  60 MW

(b)  54 MW

(c)  125 MW

(d) 35 MW

Answer: (a)

16. A charged particle (mass m and charge q) moves along X axis with velocity V0. When it passes through the origin it enters a region having uniform electric field  which extends upto x = d. Equation of path of electron in the region x > d is:

(a) 

(b) 

(c) 

(d) 

Answer: (b)

17. Train A and train B are running on parallel tracks in the opposite directions with speeds of 36 km/hour and 72 km/hour, respectively. A person is walking in train A in the direction opposite to its motion with a speed of 1.8 km/hour. Speed (in ms–1) of this person as observed from train B will be close to:

(a)  29.5 ms1

(b)  30.5 ms1

(c)  31.5 ms1

(d) 28.5 ms1

Answer: (a)

18. Shown in the figure is rigid and uniform one meter long rod AB held in horizontal position by two strings tied to its ends and attached to the ceiling. The rod is of mass `m` and has another weight of mass 2 m hung at a distance of 75 cm from A. The tension in the string at A is:

(a)  0.75 mg

(b)  0.5 mg

(c)  1 mg

(d) 2 mg

Answer: (c)

19. The least count of the main scale of a vernier callipers is 1 mm. Its vernier scale is divided into 10 divisions and coincide with 9 divisions of the main scale. When jaws are touching each other, the 7th division of vernier scale coincides with a division of main scale and the zero of vernier scale is lying right side of the zero of main scale. When this vernier is used to measure length of a cylinder the zero of the vernier scale between 3.1 cm and 3.2 cm and 4th VSD coincides with a main scale division. The length of the cylinder is: (VSD is vernier scale division)

(a)  3.21 cm

(b)  3.07 cm

(c)  2.99 cm

(d) 3.2 cm

Answer: (b)

20. A particle of mass m with an initial velocity  collides perfectly elastically with a mass 3m at rest. It moves with a velocity  after collision, then v is given by:

(a) 

(b) 

(c) 

(d) 

Answer: (d)

21. A small block starts slipping down from a point B on an inclined plane AB, which is making an angle θ with the horizontal section BC is smooth and the remaining section CA is rough with a coefficient of friction. It is found that the block comes to rest as it reaches the bottom (point A) of the inclined plane. If BC = 2AC, the coefficient of friction is given by μ =k tan θ. The value of k is __________

Answer: (c)

22. An engine takes in 5 moles of air at 20°C and 1atm, and compresses it adiabaticaly to 1/10th of the original volume. Assuming air to be a diatomic ideal gas made up of rigid molecules, the change in its internal energy during this process comes out to be X kJ. The value of X to the nearest integer is ___________.

Answer: (46 kJ)

23. When radiation of wavelength λ is used to illuminate a metallic surface, the stopping potential is V. When the same surface is illuminated with radiation of wavelength 3 λ, the stopping potential is V/4. If the threshold wavelength for the metallic surface is n λ then value of n will be __________.

Answer: (9𝛌)

24. A circular coil of radius 10 cm is placed in uniform magnetic field of 3.0 × 10–5 T with its plane perpendicular to the field initially. It is rotated at constant angular speed about an axis along the diameter of coil and perpendicular to magnetic field so that it undergoes half of rotation in 0.2s. The maximum value of EMF induced (in μV) in the coil will be close to the integer __________.

Answer: (15 𝛍V)

25. A 5μF capacitor is charged fully by a 220V supply. It is then disconnected from the supply and is connected in series to another uncharged 2.5μF capacitor. If the energy change during the charge redistribution is (X/100) J then value of X to the nearest integer is _________.

Answer: (d)

Chemistry

1. The increasing order of the following compounds towards HCN addition is:

(1)  (iii) < (i) < (iv) < (ii)

(2)  (iii) < (iv) < (i) < (ii)

(3)  (i) < (iii) < (iv) < (ii)

(4)  (iii) < (iv) < (ii) < (i)

Answer: (1)

2. Which of the following is used for the preparation of colloids?

(1)  Van Arkel Method

(2)  Ostwald Process

(3)  Mond Process

(4)  Bredig’s Arc Method

Answer: (4)

3. An open beaker of water in equilibrium with water vapour is in a sealed container. When a few grams of glucose are added to the beaker of water, the rate at which water molecules:

(1)  leaves the vapour increases

(2)  leaves the solution increases

(3)  leaves the vapour decreases

(4)  leaves the solution decreases

Answer: (1)

4. For octahedral Mn(II) and tetrahedral Ni(II) complexes, consider the following statements:

(I) both the complexes can be high spin.

(II) Ni(II) complexes can very rarely be low spin.

(III) with strong field ligands, Mn(II) complexes can be low spin.

(IV) the aqueous solution of Mn(II) ions is yellow in colour.

The correct statements are:

(1)  (I), (III) and (IV) only

(2)  (I), (II) and (III) only

(3)  (II), (III) and (IV) only

(4)  (I) and (II) only

Answer: (2)

5. The statement that is not true about ozone is:

(1)  in the stratosphere, it forms a protective shield against UV radiation.

(2)  in the atmosphere, it is depleted by CFCs.

(3)  in the stratosphere, CFCs release chlorine-free radicals (Cl) which reacts with O3 to give chlorine dioxide radicals.

(4)  it is a toxic gas and its reaction with NO gives NO2.

Answer: (c)

6. Consider the following reactions:

‘x’, ‘y’ and ‘z’ in these reactions are respectively.

(1)  4, 5 & 6

(2)  5, 4 & 5

(3)  5, 6 & 5

(4)  4, 6 & 5

Answer: (4)

7. The IUPAC name for the following compound is:

(1)  2,5-dimethyl-5-carboxy-hex-3-enal

(2)  2,5-dimethyl-6-oxo-hex-3-enoic acid

(3)  6-formyl-2-methyl-hex-3-enoic acid

(4)  2,5-dimethyl-6-carboxy-hex-3-enal

Answer: (2)

8. For the following Assertion and Reason, the correct option is

Assertion (A): When Cu (II) and Sulphide ions are mixed, they react together extremely quickly to give a solid.

Reason (R): The equilibrium constant of Cu2+ (aq) + S2– (aq) ⇌ CuS (s) is high because the solubility product is low.

(1)  (A) is false and (R) is true.

(2)  Both (A) and (R) are false.

(3)  Both (A) and (R) are true but (R) is not the explanation for (A).

(4)  Both (A) and (R) are true but (R) is the explanation for (A).

Answer: (4)

9. Which one of the following graphs is not correct for an ideal gas?

d = Density, P = Pressure, T = Temperature

The correct statements are:

(1)  (i)

(2)  (iv)

(3)  (iii)

(4)  (ii)

Answer: (4)

10. While titrating dilute HCl solution with aqueous NaOH, which of the following will not be required?

(1)  Bunsen burner and measuring cylinder

(2)  Burette and porcelain tile

(3)  Clamp the phenolphthalein

(4)  Pipette and distilled water

Answer: (1)

11. In Carius’ method of estimation of halogen, 0.172 g of an organic compound showed the presence of 0.08 g of bromine. Which of these is the correct structure of the compound?

Answer: (c)

12. On heating compound (A) gives a gas (B) which is a constituent of air. This gas when treated with H2 in the presence of a catalyst gives another gas (C) which is basic in nature. (A) should not be:

(1)  (NH4)2Cr2O7

(2)  NaN3

(3)  NH4NO2

(4)  Pb(NO3)2

Answer: (4)

13. The major product in the following reaction is:

Answer: (3)

14. In general, the property (magnitudes only) that shows an opposite trend in comparison to other properties across a period is:

(1)  Ionization enthalpy

(2)  Electronegativity

(3)  Atomic radius

(4)  Electron gain enthalpy

Answer: (3)

15. The figure that is not a direct manifestation of the quantum nature of atoms is:

Answer: (4)

16. The major aromatic product C in the following reaction sequence will be:

Answer: (3)

17. Consider that a d6 metal ion (M2+) forms a complex with aqua ligands, and the spin only magnetic moment of the complex is 4.90 BM. The geometry and the crystal field stabilization energy of the complex is:

(1)  tetrahedral and –0.6Δt

(2)  tetrahedral and –1.6Δt + 1P

(3)  octahedral and –1.6Δ0

(4)  octahedral and –2.4Δ0 + 2P

Answer: (1)

18. If AB4 molecule is a polar molecule, a possible geometry of AB4 is:

(1)  Square planar

(2)  Tetrahedral

(3)  Square pyramidal

(4)  Rectangular planar

Answer: (1)

19. Which of the following compounds will show retention in the configuration on nucleophilic substitution by OH ion?

Answer: (1)

20. The metal mainly used in devising photoelectric cells is:

(1)  Li

(2)  Cs

(3)  Rb

(4)  Na

Answer: (b)

21. The mass of gas adsorbed, x, per unit mass of adsorbate, m, was measured at various pressures, p. A graph between log [x / m] and log p gives a straight line with slope equal to 2 and the intercept equal to 0.4771. The value of [x / m] at a pressure of 4 atm is: (Given log 3 = 0.4771)

Answer: (48)

22. The Gibbs energy change (in J) for the given reaction at [Cu2+] = [Sn2+] = 1 M and 298 K is:

Cu(s) + Sn2+ (aq.) → Cu2+(aq.) + Sn(s)

Answer: (96500 Joules)

23. The internal energy change (in J) when 90 g of water undergoes complete evaporation at 100ºC is __________.

(Given: ΔHvap for water at 373 K = 41 kJ/mol, R = 8.314 JK–1 mol–1)

Answer: (189494.39)

24. The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are x, y and z. The sum of x, y and z is _____.

Answer: (6)

25. The number of chiral carbons present in the molecule given below is ________.

Answer: (5)

Mathematics

1. A line parallel to the straight line 2x – y = 0 is tangent to the hyperbola  at the point (x1,  y1). Then  is equal to :

(1)  6

(2)  10

(3)  8

(4)  5

Answer: (1)

2. The domain of the function  is (−∞, −a] ∪ [a, ∞). Then a is equal to :

(1) 

(2) 

(3) 

(4) 

Answer: (3)

3. If a function f(x) defined by  be continuous for some a, b, c ∈ R and f´(0) + f´(2) = e, then the value of a is:

(1) 

(2) 

(3) 

(4) 

Answer: (4)

4. The sum of the first three terms of a G.P. is S and their product is 27. Then all such S lie in

(1)  (−∞,−9]∪[3, ∞)

(2)  [−3, ∞)

(3)  (−∞,−9]

(4)  (−∞,−3]∪[9, ∞)

Answer: (d)

5. If R = {(x,y) : x,y ∈ Z, x2 + 3y2 ≤ 8} is a relation on the set of integers Z, then the domain of R−1 is:

(1)  {−1, 0, 1}

(2)  {−2, −1, 1, 2}

(3)  {0,1}

(4)  {-2,-1,0,1,2}

Answer: (1)

6. The value of  is :

(1) 

(2) 

(3) 

(4) 

Answer: (3)

7. Let P(h, k) be a point on the curve y = x2 + 7x + 2, nearest to the line, y = 3x – 3. Then the equation of the normal to the curve at P is:

(1)  x + 3y – 62 = 0

(2)  x – 3y – 11 = 0

(3)  x – 3y + 22 = 0

(4)  x + 3y + 26 = 0

Answer: (4)

8. Let A be a 2×2 real matrix with entries from {0,1} and A ≠ 0. Consider the following two statements:

(P) If A ≠I2, then A = -1

(Q) If A =1, then tr(A) = 2,

where I2 denotes 2 × 2 identity matrix and tr(A) denotes the sum of the diagonal entries of A. Then:

(1)  Both (P) and (Q) are false

(2)  (P) is true and (Q) is false

(3)  Both (P) and (Q) are true

(4)  (P) is false and (Q) is true

Answer: (4)

9. Box I contains 30 cards numbered 1 to 30 and Box II contains 20 cards numbered 31 to 50. A box is selected at random and a card is drawn from it. The number on the card is found to be a non-prime number. The probability that the card was drawn from Box I is:

(1)  4/17

(2)  8/17

(3)  2/5

(4)  2/3

Answer: (2)

10. If p(x) be a polynomial of degree three that has a local maximum value 8 at x = 1 and a local minimum value 4 at x = 2; then p(0) is equal to :

(1)  12

(2)  −12

(3)  −24

(4)  6

Answer: (2)

11. The contra positive of the statement “If I reach the station in time, then I will catch the train” is:

(1)  If I will catch the train, then I reach the station in time.

(2)  If I do not reach the station in time, then I will catch the train.

(3)  If I do not reach the station in time, then I will not catch the train.

(4)  If I will not catch the train, then I do not reach the station in time.

Answer: (4)

12. Let α and β be the roots of the equation, 5x2 + 6x − 2 = 0. If Sn = αn + βn, n = 1,2,3,.. then:

(1)  5S6 + 6S5 + 2S4 = 0

(2)  6S6 + 5S5 = 2S4

(3)  6S6 + 5S5 + 2S4 = 0

(4)  5S6 + 6S5 = 2S4

Answer: (4)

13. If the tangent to the curve y = x+sin y at a point (a,b) is parallel to the line joining (0, 3/2) and (1/2, 2), then:

(1)  b = (π/2) + a

(2)  |a + b| = 1

(3)  |b – a| = 1

(4)  b = a

Answer: (3)

14. Area (in sq. units) of the region outside  and inside the ellipse  is:

(1)  3(π – 2)

(2)  6(π – 2)

(3)  6(4 – π)

(4)  3(4 – π)

Answer: (2)

15. If |x| < 1, |y| < 1 and x ≠ y, then the sum of infinity of the following series (x + y) + (x2 + + xy + y2) + (x3 + x2y + xy2 + y3)+… is:

(1) 

(2) 

(3) 

(4) 

Answer: (2)

16. Let α > 0, β > 0 be such that α3 + β2 = 4. If the maximum value of the term independent of x in the binomial expansion of (αx1/9 + βx1/6)10 is 10k, then k is equal to:

(1)  176

(2)  336

(3)  352

(4)  84

Answer: (2)

17. Let S be the set of all λ ∈ R for which the system of linear equations

2x – y + 2z = 2

x – 2y + λz = −4

x + λy + z = 4

has no solution. Then the set S

(1)  is an empty set.

(2)  is a singleton.

(3)  contains more than two elements.

(4)  contains exactly two elements.

Answer: (4)

18. Let X = {x ∈ N: 1 ≤ x ≤ 17} and Y = {ax + b : x ∈ X and a, b ∈ R, a > 0}. If mean and variance of elements of Y are 17 and 216 respectively then a + b is equal to:

(1)  −27

(2)  7

(3)  −7

(4)  9

Answer: (3)

19. Let y = y(x) be the solution of the differential equation,  If y(π) = a, and dy/dx at x = π is b, then the ordered pair (a, b) is equal to :

(1)  (2, 3/2)

(2)  (1, 1)

(3)  (2, 1)

(4)  (1, −1)

Answer: (2)

20. The plane passing through the points (1,2,1), (2,1,2) and parallel to the line, 2x = 3y, z = 1 also passes through the point:

(1)  (0, −6, 2)

(2)  (0, 6, −2)

(3)  (−2, 0, 1)

(4)  (2, 0, −1)

Answer: (c)

21. The number of integral values of k for which the line, 3x + 4y = k intersects the circle, x2 + y2 − 2x – 4y + 4 = 0 at two distinct points is…

Answer: (9)

22. Let  be three unit vectors such that  Then  is equal to:

Answer: (2)

23. If the letters of the word ’MOTHER’ be permuted and all the words so formed (with or without meaning) be listed as in a dictionary, then the position of the word ’MOTHER’ is….

Answer: (309)

24. If  (n ∈ N) then the value of n is equal to:

Answer: (40)

25. The integral  is equal to:

Answer: (1.5)

JEE Main January 9 2020 Shift 2 Question Paper with Answer Key

Physics

1. An electron gun is placed inside a long solenoid of radius R on its axis. The solenoid has  and carries a current i. The electron gun shoots an electron along the radius of solenoid with speed If the electron does not hit the surface of the solenoid, maximum possible value of v is (all symbols have their standard meaning):

(a) 

(b) 

(c) 

(d) 

Answer: (b)

2. Two identical capacitors A and B, charged to the same potential 5V are connected in two different circuit as shows below at time t=0. If the charges on capacitors A and B at time t= CR is QA and QB respectively, then (Here is the base of natural logarithm)

(a)  CV, CV/e

(b)  CV/e, CV/2e

(c)  CV/e, VC/2

(d) CV/e, CV

Answer: (a)

3. For the four sets of three measured physical quantities as given below. Which of the following options is correct?

(i) A1 = 24.36, B1=0.0724, C1= 256.2

(ii) A2 = 24.44, B2=16.08, C2= 240.2

(iii) A3 = 25.2, B3 = 19.2812, C3= 236.183

(iv) A4 = 25, B4 = 236.191, C4 = 19.5

(a)  A4 + B4 + C4 < A1 + B1 + C1 < A2 + B2 + C2 = A3 + B3 +C3

(b)  A1 + B1 + C1 = A2 + B2 + C2 = A3 + B3 + C3 = A4 + B4 + C4

(c)  A1 + B1 + C1 < A3 + B3 +C3 < A2 + B2 + C2 < A4 + B4 +C4

(d) A4 + B4 +C4 < A1 + B1 +C1< A3 + B3 +C3 < A2 + B2 +C2

Answer: (a)

4. A particle starts from the origin at t = 0 with an initial velocity of from origin and moves in the x-y plane with a constant acceleration  The x-coordinate of the particle at the instant when its y-coordinated is 32 m is D meters. The value of D is:

(a)  60

(b)  50

(c)  32

(d) 40

Answer: (a)

5. A spring mass system (mass m, spring constant k and natural length l) rest in equilibrium on a horizontal disc. The free end of the spring is fixed at the center of the disc. If the disc together with spring mass system, rotates about its axis with an angular velocity (k >>> mω2), the relative change in the length of the spring is best given by the option:

(a) 

(b) 

(c) 

(d) 

Answer: (c)

6. A small circular loop of conducting wire has radius a and carries current i. It is placed in a uniform magnetic field B perpendicular to its plane such that when rotated slightly about its diameter and released, its starts performing simple harmonic motion of time period T. If the mass of the loop is m then

(a) 

(b) 

(c) 

(d) 

Answer: (b)

7. A small spherical droplet of density d is floating exactly half immersed in a liquid of density ρ and surface tension T. The radius of droplet is (take note that the surface tension applied an upward force on droplet)

(a) 

(b) 

(c) 

(d) 

Answer: (d)

8. A wire of length L and mass 6 x 103 kg/m per unit length is put under tension of 540N. Two consecutive frequencies that it resonates at are: 420 Hz and 490 Hz . Then L in meter is

(a)  8.1 m

(b)  2.1 m

(c)  1.1 m

(d) 5.1 m

Answer: (b)

9. A plane electromagnetic wave is propagating along the direction  with the polarization along the direction   The correct form of the magnetic field of the wave would be (here B0 is an appropriate constant)

(a) 

(b) 

(c) 

(d) 

Answer: (a)

10. Two gases-Argon (atomic radius 0.07 nm atomic weight 40) and Xenon (atomic radius 0.1 nm atomic weight 140) have the same number density and are at the same temperature. The ratio of their respective mean free time is closest to

(a)  4.67

(b)  2.04

(c)  1.83

(d) 3.67

Answer: (c)

11. Two steel wires having same length are suspended from a ceiling under the same load. If the ratio of their energy stored per unit volume is 1: 4, the ratio of their diameters is:

(a)  √2:1

(b)  1:√2

(c)  1:2

(d) 2:1

Answer: (a)

12. Planets A has a mass M and radius R. Planet B has the mass and half the radius of planet A. If the escape velocities from the planets A and B are vA and vB respectively, then surfaces is the value of n is:

(a)  3

(b)  2

(c)  4

(d) 5

Answer: (c)

13. A rod of length L has non-uniform linear mass density given by  where a and b are constants and 0 ≤ x ≤ The value of x for the center of mass of the rod is at:

(a) 

(b) 

(c) 

(d) 

Answer: (b)

14. A particle of mass m is projected with a speed u from the ground at angle is θ = π/3 w.r.t. horizontal (x-axis). When it has reached its maximum height, it collides completely inelastically with another particle of the same mass and velocity  The horizontal distance covered by the combined mass before reaching the ground is:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

15. A uniformly thick wheel with moment of inertia I and radius R is free to rotate about its center of mass (see fig). A massless string is wrapped over its rim and two blocks of massless string is wrapped over its rim and two blocks of masses m1 and m2 (m1 > m2 ) are attached to the ends of string. The system is released from rest. The angular speed of the wheel when m1 descend by a distance h is:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

16. The energy required to ionise a hydrogen like ion in its ground state is 9 Rydbergs. What is the wavelength of the radiation emitted when the electron in this ion jumps from the second excited state to the ground stare?

(a)  8.6

(b)  11.4

(c)  24.2

(d) 35.8

Answer: (b)

17. There is a small source of light at some depth below the surface of water (refractive index 4/3) in a tank of large cross sectional surface area. Neglecting any reflection from the bottom and absorption by water, percentage of light that emerges out of surface is (nearly): [Use the fact that surface area of a spherical cap of height h and radius of curvature r is 2πrh]

(a)  17%

(b)  34%

(c)  50%

(d) 21%

Answer: (a)

18. An electron of mass m and magnitude of charge |e| initially at rest gets accelerated by a constant electric field E. The of charge of de-Broglie wavelength of this electron at time t ignoring relativistic effects is

(a) 

(b) 

(c) 

(d) 

Answer: (c)

19. In LC circuit the inductance L = 40mH and C = 100 μF. If a voltage V(t) = 10sin(314t) is applied to the circuit, the current in the circuit is given as

(a)  10cos (314t)

(b)  0.52cos (314t)

(c)  0.52sin (314t)

(d) 5.2cos (314t)

Answer: (b)

20. The current (i) in the network is

(a)  0 A

(b)  0.3 A

(c)  0.2 A

(d) 0.6 A

Answer: (b)

21. Starting at temperature 300 K, one mole of an ideal diatomic gas (γ = 1.4) is first compressed adiabatically from volume to V1 to V2 = V1/16. It is then allowed to expand isobarically to volume 2V2 . If all the processes are the quasi-static then the final temperature of the gas (0K) is (to the nearest integer)

Answer: (1818 K)

22. An electric field  passes through the box shown in figure. The flux of the electric field through surface ABCD and BCGF are marked as ϕ1 and ϕ2, then difference between 

Answer: (48 Nm2/C)

23. In a Young’s double slit experiment 15 fringes are observed on a small portion of the screen when light of wavelength 500nm is used. 10 fringes are observed on the same section of the screen when another light source of wavelength λ is used. Then the value of λ is (nm)

Answer: (750 nm)

24. In a meter bridge experiment S is a standard resistance. R is a resistance wire. It is found that balancing length is l = 25 cm. If R is replaced by a wire of half length and half diameter that of R of same material, then the balancing l (in cm) will now be

Answer: (40)

25. The circuit shown below is working as a 8V dc regulated voltage source. When 12V is used as input, the power dissipated (in mW) in each diode id; (considering both zener diode are identical).

Answer: (40 mW)

Chemistry

1. 5 g of Zinc is treated separately with an excess of

(I) dilute hydrochloric acid and

(II) aqueous sodium hydroxide.

The ratio of the volumes of H2 evolved in these two reactions is:

(a)  2 : 1

(b)  1 : 2

(c)  1 : 1

(d) 1 : 4

Answer: (c)

2. The solubility product of Cr(OH)3 at 298 K is 6×1031 . The concentration of hydroxide ions in a saturated solution Cr(OH)3 will be:

(a)  (18×1031)1/4

(b)  (18×1031)1/2

(c)  (2.22×1031)1/4

(d) (4.86×1031)1/4

Answer: (a)

3. Among the statements (a)-(d), the correct ones are:

(a) Lithium has the highest hydration enthalpy among the alkali metals.

(b) Lithium chloride is insoluble in pyridine.

(c) Lithium cannot form ethynide upon its reaction with ethyne.

(d) Both lithium and magnesium react slowly with H2O.

(a)  (a), (b) and (d) only

(b)  (b) and (c) only

(c)  (a), (c) and (d) only

(d) (a) and (d) only

Answer: (a)

4. The first and second ionization enthalpies of a metal are 496 and 4560 kJ mol1 How many moles of HCl and H2SO4, respectively, will be needed to react completely with 1 mole of metal hydroxide?

(a)  1 and 2

(b)  1 and 0.5

(c)  1 and 1

(d) 2 and 0.5

Answer: (b)

5. In the figure shown below reactant A (represented by the square) is in equilibrium with product B (represented by circle). The equilibrium constant is:

(a)  1

(b)  2

(c)  8

(d) 4

Answer: (b)

6. The correct order spin-only magnetic moments of the following complexes is:

I. [Cr(H2O)6]Br2

II. Na4[FeCN6]

III. Na3[Fe(C2O4)3] (∆0 > P)

IV. (Et4N)2[CoCl4]

(a)  (III)>(I)>(II)>(IV)

(b)  (III)>(I)>(IV)>(II)

(c)  (I)>(IV)>(III)>(II)

(d) (II)≈(I)>(IV)>(III)

Answer: (c)

7. The true statement amongst the following.

(a)  S is a function of temperature but S is not a function of temperature.

(b)  Both S and S are functions of temperature.

(c)  Both S and S are not functions of temperature.

(d) S is not a function of temperature but S is a function of temperature.

Answer: (b)

8. The reaction of H3N3B3Cl3 (A) with LiBH4 in tetrahydrofuran gives inorganic benzene (B). Furthur, the reaction of (A) with (C) leads to H3N3B3(Me)3. Compounds (B) and (C) respectively, are:

(a)  Boron nitride, MeBr

(b)  Diborane, MeMgBr

(c)  Borazine, MeBr

(d) Borazine, MeMgBr

Answer: (d)

9. A mixture of gases O2, H2 and CO are taken in a closed vessel containing charcoal. The graph that represents the correct behaviour of pressure with time is:

Answer: (c)

10. The isomer(s) of [Co(NH3)4Cl2] that has/have a Cl-Co-Cl angle of 90°, is/are:

(a)  cis only

(b)  trans only

(c)  meridional and trans

(d) cis and trans

Answer: (a)

11. Amongst the following, the form of water with lowest ionic conductance at 298 K is:

(a)  distilled water

(b)  sea water

(c)  saline water used for intra venous injection

(d) water from a well

Answer: (a)

12. The number of sp2 hybrid orbitals in molecule of benzene is:

(a)  18

(b)  24

(c)  6

(d) 12

Answer: (a)

13. Which of the following reactions will not produce a racemic product?

Answer: (b)

14. Which of the following has the shortest C-Cl bond?

(a)  Cl―CH=CH2

(b)  Cl―CH=CH―CH3

(c)  Cl―CH=CH―OCH3

(d) Cl―CH=CH―NO2

Answer: (d)

15. Biochemical oxygen demand (BOD) is the amount of oxygen required (in ppm):

(a)  for the photochemical breakdown of waste present in 1m3 volume of a water body.

(b)  by anaerobic bacteria to break-down inorganic waste present in a water body.

(c)  by bacteria to break-down organic waste in a certain volume of water sample.

(d) for sustaining life in a water body.

Answer: (c)

16. Which polymer has chiral, monomer(s)?

(a)  Buna-N

(b)  Neoprene

(c)  Nylon 6,6

(d) PHBV

Answer: (d)

17. A, B and C are three biomolecules. The results of the tests performed on them are given below:

Molisch’s Test Barfoed Test Biuret Test
A Positive Negative Negative
B Positive Positive Negative
C Negative Negative Positive

A, B and C are respectively

(a)  A = Lactose B = Glucose C = Albumin

(b)  A = Lactose B = Glucose C = Alanine

(c)  A = Lactose B = Fructose C = Alanine

(d) A = Glucose B = Sucrose C = Albumin

Answer: (a)

18. The decreasing order of basicity of the following amines is:

(a)  I > II > III > IV

(b)  IV > III > I > II

(c)  II > I > III > IV

(d) IV > I > II > III

Answer: (b)

19. 

The compound [P] is

Answer: (b)

20. In the following reaction A is :

Answer: (d)

21. The sum of total number of bonds between chromium and oxygen atoms in chromate and dichromate ions is:

Answer: (12)

22. A sample of milk splits after 60 min. at 300K and after 40 min at 400K when the population of lactobacillus acidophilus in it doubles . The activation energy (in kJ/mol) for this process is closest to : (Given, R = 8.3 J mol1K1), ln(2/3) = 0.4, e3 = 4.0)

Answer: (3.98)

23. One litre of sea water (d =1.03g/cm3) contains 10.3 mg of O2 Determine the concentration of O2 in ppm:

Answer: (10.00)

24. A cylinder containing an ideal gas (0.1 mol of 1.0 dm3 ) is in thermal equilibrium with a large volume of 0.5 molal aqueous solution of ethylene glycol at it freezing point. If the stoppers S1 and S2 (as shown in the figure) suddenly withdrawn, the volume of the gas in liters after equilibrium is achieved will be: (Given, Kf (water) = 2.0 K kg mol1 ,R = 0.08 dm3 atm K1 mol1)

Answer: (2.18)

25. Consider the following reactions;

The mass percentage of carbon in A is:

Answer: (66.67)

Mathematics

1. If A = {x∈ R∶ |x| <2} and B = {x∈ R∶ |x−2| ≥3} then :

(a)  A − B = [−1,2]

(b)  B − A = R− (−2, 5)

(c)  A ⋃ B = R− (2,5)

(d) A ∩ B = (−2, −1)

Answer: (b)

2. If 10 different balls has to be placed in 4 distinct boxes at random, then the probability that two of these boxes contain exactly 2 and 3 balls is :

(a)  965/210

(b)  945/210

(c)  945/211

(d) 965/211

Answer: (b)

3. If x = 2 sin θ − sin 2 θ and y = 2 cos θ − cos 2 θ, θ ∈ [0, 2π], then d2y/dx2 at θ =π is:

(a)  −3/8

(b)  3/4

(c)  3/2

(d) −3/4

Answer: (*)

4. Let f and g be differentiable functions on R, such that fog is the identity function. If for some a, b ∈ R, g’(a) = 5 and g(a) = b, then f'(b) is equal to :

(a)  2/5

(b)  5

(c)  1

(d) 1/5

Answer: (d)

5. In the expansion of  if l1 is the least value of the term independent of x when  and l2 is the least value of the term independent of x when  then the ratio l2 : l1 is equal to:

(a)  16 : 1

(b)  8 : 1

(c)  1 : 8

(d) 1 : 16

Answer: (a)

6. Let a,b ∈R, a ≠ 0, such that the equation, ax2-2bx + 5 = 0 has a repeated root α, which is also a root of the equation x2 − 2bx − 10 = 0. If β is the root of this equation, then α2 + β2 is equal to:

(a)  24

(b)  25

(c)  26

(d) 28

Answer: (b)

7. Let a function f: [0, 5] → R, be continuous, f(1) = 3 and F be defined as:

 

Then for the function F, the point x = 1 is

(a)  a point of inflection.

(b)  a point of local maxima

(c)  a point of local minima

(d) not a critical point

Answer: (c)

8. Let [t] denotes the greatest integer ≤ t and  Then the function, f(x) = [x2] sin πx discontinuous, when x is equal to

(a) 

(b)  √A

(c) 

(d) 

Answer: (a)

9. Let a – 2b + c = 1

If   then:

(a)  f(−50) = 501

(b)  f(−50) = −1

(c)  f(50) = 1

(d) f(50) = −501

Answer: (c)

10. Given:  and  Then the area (in sq. units) of the region bounded by the curves y = f(x) and y = g(x) between the lines 2x = 1 to 2x = √3 is:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

11. The following system of linear equations

7x + 6y – 2z = 0

3x + 4y + 2z = 0

x – 2y – 6z = 0, has

(a)  infinitely many solutions, (x, y, z) satisfying y = 2z

(b)  infinitely many solutions (x, y, z) satisfying x = 2z

(c)  no solution

(d) only the trivial solution

Answer: (b)

12. If p − > (p ∧~ q) is false. Then the truth values of p and q are respectively

(a)  F, T

(b)  T, F

(c)  F, F

(d) T, T

Answer: (d)

13. The length of minor axis (along y-axis) of an ellipse of the standard form is 4/√3. If this ellipse touches the line x + 6y = 8, then its eccentricity is:

(a) 

(b) 

(c) 

(d) 

Answer: (b)

14. If z be a complex number satisfying |Re(z)| + |Im(z)| = 4, then |𝑧| cannot be:

(a)  √7

(b) 

(c)  √10

(d) √8

Answer: (a)

15. If  and   where 0 < θ < π/4, then:

(a)  y(1 + x) = 1

(b)  x(1 – y) = 1

(c)  y(1 – x) = 1

(d) x(1 + y) = 1

Answer: (c)

16. If  then a value of x satisfying y(x) = e is:

(a)  √3e

(b) 

(c)  √2e

(d) e/√2

Answer: (a)

17. If one end of focal chord AB of the parabola y2 = 8x is at A(1/2, −2), then the equation of tangent to it at B is

(a)  x + 2y + 8 = 0

(b)  2x – y – 24 = 0

(c)  x – 2y + 8 = 0

(d) 2x + y – 24 = 0

Answer: (c)

18. Let an be the nth term of a G.P. of positive terms. If  then  is equal to:

(a)  300

(b)  175

(c)  225

(d) 150

Answer: (d)

19. A random variable X has the following probability distribution:

X 1 2 3 4 5
P(X) K2 2K K 2K 5K2

Then P(X > 2) is equal to:

(a)  7/12

(b)  23/36

(c)  1/36

(d) 1/6

Answer: (b)

20. If  where C is constant if integration, then the ordered pair (λ, f(θ)) is equal to:

(a)  (−1, 1 – tan θ)

(b)  (−1, 1 + tan θ)

(c)  (1, 1 + tan θ)

(d) (1, 1 – tan θ)

Answer: (b)

21. Let  be three vectors such that  and the angle between is π/3. If   is perpendicular to vector  is equal to______

Answer: (30)

22. If Cr = 25Cr and C0 + 5 ∙ C1 + 9 ∙ C2 + … + 101 ∙ C25 = 225 ∙ k is equal to ________.

Answer: (51)

23. If the curves x2 − 6x + y2 +8 = 0 and x2 − 8y + y2 + 16 − k = 0, (k > 0) touch each other at a point, then the largest value of k is

Answer: (36)

24. The number of terms common to the A.P.’s 3,7,11,…407 and 2,9,16,…709 is __________.

Answer: (14)

25. If the distance between the plane. 23x – 10y – 2z + 48 = 0 and the plane containing the lines  and  (λ ∈ R) is equal to  then k is equal to ________.

Answer: (3)

JEE Main January 9 2020 Shift 1 Question Paper with Answer Key

Physics

1. Three identical solid spheres each have mass ‘m’ and diameter ‘d’ are touching each other as shown in the figure. Calculate ratio of moment of inertia about the axis perpendicular to plane of paper and passing through point P and B as shown in the figure. Given P is centroid of the triangle.

(a)  13/23

(b)  13/15

(c)  15/13

(d) 23/13

Answer: (a)

2. A solid sphere having a radius R and uniform charge density ρ. If a sphere of radius R/2 is carved out of it as shown in the figure. Find the ratio of the magnitude of electric field at point A and B

(a)  17/54

(b)  18/54

(c)  18/34

(d) 21/34

Answer: (c)

3. Consider an infinitely long current carrying cylindrical straight wire having radius ‘a’. Then the ratio of magnetic field due to wire at distance a/3 and 2a, respectively from axis of wire is

(a)  3/2

(b)  2/3

(c)  2

(d) 1/2

Answer: (b)

4. Particle moves from point A to point B along the line shown in figure under the action of force Determine the work done on the particle by  in moving the particle from point A to point B (all quantities are in SI units)

(a)  1J

(b)  1/2 J

(c)  2 J

(d) 3/2 J

Answer: (a)

5. For the given P-V graph of an ideal gas, chose the correct V-T graph. Process BC is adiabatic. (Graphs are schematic and not to scale).

Answer: (a)

6. An electric dipole of moment  is at the origin (0, 0, 0). The electric field due to this dipole at is parallel to [Note that  ]

(a) 

(b) 

(c) 

(d) 

Answer: (c)

7. A body A of mass m is revolving around a planet in a circular orbit of radius R. At the instant the particle B has velocity  , another particle of mass m/2 moving at velocity of , collides perfectly inelastically with the first particle. Then, the combined body

(a)  Fall vertically downward towards the planet.

(b)  Continue to move in a circular orbit

(c)  Escape from the Planet’s Gravitational field

(d) Start moving in an elliptical orbit around the planet

Answer: (d)

8. Two particles of equal mass m have respective initial velocities  They collide completely inelastically. Find the loss in kinetic energy.

(a)  3mu2/4

(b)  √2mu2/√3

(c)  mu2/3

(d) mu2/8

Answer: (d)

9. Three harmonic waves of same frequency (v) and intensity (I0) having initial phase angles 0, π/4, −π/4 rad respectively. When they are superimposed, the resultant intensity is close to;

(a)  5.8I0

(b)  I0

(c)  3I0

(d) 0.2I0

Answer: (a)

10. An ideal liquid (water) flowing through a tube of non-uniform cross-sectional area, where area at A and B are 40 cm2 and 20 cm2 If pressure difference between A & B is 700 N/m2, then volume flow rate is (density of water = 1000 kgm−3)

(a)  2720 cm

(b)  2420 cm

(c)  1810 cm

(d) 3020 cm

Answer: (a)

11. A screw gauge advances by 3 mm on main scale in 6 rotations. There are 50 divisions on circular scale. Find least count of screw gauge?

(a)  0.01 cm

(b)  0.001 cm

(c)  0.001 mm

(d) 0.02 mm

Answer: (b)

12. A telescope of aperture diameter 5 m is used to observe the moon from the earth. Distance between the moon and earth is 4 × 105 The minimum distance between two points on the moon’s surface which can be resolved using this telescope is close to (Wavelength of light is 5500 Å )

(a)  60 m

(b)  20 m

(c)  600 m

(d) 200 m

Answer: (a)

13. Radiation with wavelength 6561 Å falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of 3×104 If the radius of largest circular path followed by electron is 10 mm, the work function of metal is close to;

(a)  1.8 eV

(b)  0.8 eV

(c)  1.1 eV

(d) 1.6 eV

Answer: (c)

14. Kinetic energy of the particle is 𝐸 and it’s de–Broglie wavelength is λ. On increasing its K.E by ΔE, it’s new de–Broglie wavelength becomes λ/2. Then ΔE is

(a)  3E

(b)  2E

(c)  2E

(d) 4E

Answer: (a)

15. A quantity is given by , where c is speed of light, G is universal gravitational constant and h is the Planck’s constant. Dimension of f is that of;

(a)  area

(b)  energy

(c)  volume

(d) momentum

Answer: (b)

16. A vessel of depth 2h is half filled with a liquid of refractive index √2 in upper half and with a liquid of refractive index 2√2 in lower half. The liquids are immiscible. The apparent depth of inner surface of the bottom of the vessel will be;

(a)  3h√2/4

(b)  h/√2

(c)  h/3√2

(d) h/2(√2+1)

Answer: (a)

17. In the given circuit diagram, a wire is joining point B & C. Find the current in this wire;

(a)  0.4 A

(b)  2 A

(c)  0

(d) 4 A

Answer: (b)

18. Two plane electromagnetic waves are moving in vacuum in whose electric field vectors are given by  and At t = 0 A charge q is at origin with velocity   (c is speed of light in vacuum). The instantaneous force on this charge (all data are in SI units)

(a) 

(b) 

(c) 

(d) 

Answer: (b)

19. Consider two ideal diatomic gases A and B at some temperature T. Molecules of the gas A are rigid, and have a mass m. Molecules of the gas B have an additional vibration mode and have a mass m/4 . The ratio of molar specific heat at constant volume of gas A and B is;

(a)  7/9

(b)  5/9

(c)  3/5

(d) 5/7

Answer: (d)

20. A charged particle of mass ‘m’ and charge ‘q’ is moving under the influence of uniform electric field  and a uniform magnetic field  follow a trajectory from P to Q as shown in figure. The velocities at P and Q are respectively  Then which of the following statements (A, B, C, D) are correct? (Trajectory shown is schematic and not to scale)

(A) Magnitude of electric field 

(B) Rate of work done by electric field at P is 

(C) Rate of work done by both fields at Q is zero

(D) The difference between the magnitude of angular momentum of the particle at P and Q is 2mva.

(a)  A, C and D are correct

(b)  A, B and C are correct

(c)  A, B. C and D are correct

(d) B, C and D are correct

Answer: (b)

21. In a fluorescent lamp choke (a small transformer) 100 V of reversible voltage is produced when choke changes current in from 0.25 A to 0 A in 0.025 ms. The self-inductance of choke (in mH) is estimated to be;

Answer: (10)

22. A wire of length l = 0.3 m and area of cross section 10–2 cm2 and breaking stress 4.8×107 N/m2 is attached with block of mass 10 kg. Find the maximum possible value of angular velocity (rad/s) with which block can be moved in a circle with string fixed at one end.

Answer: (4)

23. The distance x covered by a particle in one dimension motion varies as with time 𝑡 as x2 = at2 + 2bt + c, where a, b, c are constants. Acceleration of particle depend on x as x–n , the value of n is;

Answer: (3)

24. A rod of length 1 m pivoted at one end is released from rest when it makes 30° from the horizontal as shown in the figure below.

If ω of rod is √n at the moment it hits the ground, then find n.

Answer: (15)

25. In the given circuit both diodes are ideal having zero forward resistance and built-in potential of 0.7 V. Find the potential of point E in volts.

Answer: (12)

Chemistry

1. The de Broglie wavelength of an electron in the 4th Bohr orbit is:

(a)  4πa0

(b)  42πa0

(c)  8πa0

(d) 6πa0

Answer: (c)

2. If the magnetic moment of a dioxygen species is 1.73 B.M, it may be:

(a)  O2, O2, or O2+

(b)  O2 or O2+

(c)  O2 or O2

(d) O2, O2+

Answer: (b)

3. If enthalpy of atomisation for Br2(l) is x kJ/mol and bond enthalpy for Br2 is y kJ/mol, the relation between them:

(a)  is x > y

(b)  is x < y

(c)  is x = y

(d) does not exist

Answer: (a)

4. Which of the following oxides are acidic, basic and amphoteric, respectively?

(a)  MgO, Cl2O, Al2O3

(b)  N2O3, Li2O, Al2O3

(c)  SO3, Al2O3, Na2O

(d) P4O10, Cl2O, CaO

Answer: (b)

5. Complex X of composition Cr(H2O)6Cln, has a spin only magnetic moment of 3.83 BM. It reacts with AgNO3 and shows geometrical isomerism. The IUPAC nomenclature of X is :

(a)  Hexaaqua chromium(III) chloride

(b)  Tetraaquadichlorido chromium(III) chloride dihydrate

(c)  Hexaaquachromium(IV) chloride

(d) Tetraaquadichlorido chromium(IV) chloride dihydrate

Answer: (b)

6. The electronic configuration of bivalent europium and trivalent cerium, are: (Atomic Number : Xe = 54, Ce = 58, Eu = 63)

(a)  [Xe]4f7, [Xe]4f1

(b)  [Xe]4f 76s2 , [Xe]4f 26s2

(c)  [Xe]4f2, [Xe]4f7

(d) [Xe]4f4, [Xe]4f9

Answer: (a)

7. The Ksp for the following dissociation is = 1.6 × 10–5. PbCl2 (s) ⇌ Pb2 + (aq) + 2Cl(aq). Which of the following choices is correct for a mixture of 300 mL 0.134 M Pb(NO3)2 and 100mL

(a)  Q > Ksp

(b)  Q < Ksp

(c)  Q = Ksp

(d) Not enough data provided

Answer: (a)

8. The compound that cannot act both as oxidising and reducing agent is :

(a)  H2SO3

(b)  HNO2

(c)  H3PO4

(d) H2O2

Answer: (c)

9. B has a smaller first ionization enthalpy than Be. Consider the following statements:

(i) It is easier to remove 2p electron than 2s electron

(ii) 2p electron of B is more shielded from the nucleus by the inner core of electrons than the 2s electron of Be

(iii) 2s electron has more penetration power than 2p electron

Atomic radius of B is more than Be (Atomic number B=5, Be=4)

The correct statements are:

(a)  (i), (ii), and (iii)

(b)  (i), (iii), and (iv)

(c)  (ii), (ii), and (iii)

(d) (i), (ii), and (iv)

Answer: (a)

10. [Pd(F)(Cl)(Br)(I)]2−,has n number of geometrical Isomers. Then, the spin-only magnetic moment and crystal field stabilisation energy [CFSE] of [Fe(CN)6]n−6 , respectively, [Note: Ignore pairing energy].

(a)  1.73 BM and −2∆0

(b)  2.84 BM and −1.6∆0

(c)  0 BM and −2.4∆0

(d) 5.92 BM and 0

Answer: (a)

11. According to the following diagram, A reduces BO2 when the temperature is:

(a)  > 1400°C

(b)  < 1400°C

(c)  > 1200°C

(d) < 1200°C

Answer: (a)

12. For following reactions

It was found that the Ea is decreased by 30 kJ/mol in the presence of catalyst. If the rate remains unchanged, the activation energy for catalysed reaction is (Assume pre exponenetial factor is same)

(a)  75 kJ/mol

(b)  135 kJ/mol

(c)  105 kJ/mol

(d) 198 kJ/mol

Answer: (c)

13. ‘X’ melts at low temperature and is a bad conductor of electricity in both liquid and solid state. X is:

(a)  Mercuty

(b)  Silicon Carbide

(c)  Zinc Sulphide

(d) Carbon Tetrachloride

Answer: (d)

14. The major product Z obtained in the following reaction scheme is:

Answer: (c)

15. Which of these will produce the highest yield in Friedel-Craft’s reaction?

Answer: (b)

16. The major product (Y) in the following reactions is :

Answer: (a)

17. The correct order of heat of combustion for following alkadienes is:

(a)  C > B > A

(b)  B > A > C

(c)  A > B > C

(d) C > A > B

Answer: (c)

18. The increasing order of basicity for the following intermediates is (from weak to strong)

(a)  A > B > D > E > C

(b)  B > A > D > C > E

(c)  A > B > E > D > C

(d) C > E > D > B > A

Answer: (a)

19. A chemist has 4 samples of artificial sweetener A, B, C and D. To identify these samples, he performed certain experiments and noted the following observations:

(i) A and D both form blue-violet colour with ninhydrin.

(ii) Lassaigne extract of C gives positive AgNO3 test and negative Fe4[Fe(CN)6]3 test.

(iii) Lassaigne extract of B and D gives positive sodium nitroprusside test.

Based on these observations which option is correct?

(a)  A – Alitame, B – Saccharin, C – Aspartame, D – Sucralose

(b)  A –Saccharin, B – Alimate, C – Sucralose, D – Aspartame

(c)  A – Aspartame, B – Alitame, C – Saccharin, D – Sucralose

(d) A – Aspartame, B – Saccharin, C – Sucralose, D – Alitame

Answer: (d)

20. Identify (A) in the following reaction sequence:

Answer: (b)

21. The molarity of HNO3 in a sample which has density 1.4 g/mL and mass percentage of 63% is :(Molecular weight of HNO3= 63).

Answer: (14)

22. The hardness of a water sample containing 103 M MgSO4 expressed as CaCO3 equivalents (in ppm)is (molar mass of MgSO4 is 120.37 g/mol)

Answer: (100.00)

23. How much amount of NaCl should be added to 600 g of water (ρ = 1.00 g/mL) to decrease the freezing point of water to −2°C? (The freezing point depression constant for water = 2 K Kg mol1)

Answer: (1.76)

24. 108 g silver (molar mass 108 g mol-1) is deposited at cathode from AgNO3(aq) solution by a certain quantity of electricity. The volume (in L) of oxygen gas produced at 273K and 1 bar pressure from water by the same quantity of electricity is

Answer: (5.8)

25. The mass percentage of nitrogen in histamine is:

Answer: (37.84)

Mathematics

1. If C be the centroid of the triangle having vertices (3, −1), (1, 3) and (2, 4). Let P be the point of intersection of the lines x + 3y − 1 = 0 and 3x − y + 1 = 0, then the line passing through the points C and P also passes through the point:

(a)  (−9, −7)

(b)  (−9, −6)

(c)  (7, 6)

(d) (9, 7)

Answer: (b)

2. The product 21/4×41/16×81/48×161/128… ..∞ to is equal to

(a)  21/4

(b)  2

(c)  21/2

(d) 1

Answer: (c)

3. A spherical iron ball of 10 cm radius is coated with a layer of ice of uniform thickness that melts at the rate of 50 cm3/min. When the thickness of ice is 5 cm, then the rate (in cm/min.) at which the thickness of ice decreases, is:

(a)  5/6π

(b)  1/54π

(c)  1/36π

(d) 1/18π

Answer: (d)

4. Let f be any function continuous on [a,b] and twice differentiable on (a,b). If for all x ∈ (a, b), f′(x) > 0 and f′′(x) < 0, then for any c ∈ (a,b),  is greater than:

(a) 

(b)  1

(c) 

(d) 

Answer: (c)

5. The value of  is:

(a)  1/4

(b)  1/2√2

(c)  1/2

(d) 1/√2

Answer: (b)

6. The number of real roots of the equation, e4x + e3x – 4e2x + ex + 1 = 0 is:

(a)  3

(b)  4

(c)  1

(d) 2

Answer: (c)

7. The value of  is equal to:

(a)  2π

(b)  4π

(c)  2π2

(d) π2

Answer: (d)

8. If for some α and β in R, the intersection of the following three planes

x + 4y − 2z = 1

x + 7y − 5z =β

x + 5y + αz = 5

is a line in R3, then α+β is equal to:

(a)  0

(b)  10

(c)  −10

(d) 2

Answer: (b)

9. If e1 and e2 are the eccentricities of the ellipse,  and the hyperbola,   respectively and (e1, e2) is a point on the ellipse, 15x2 + 3y2 = k. Then k is equal to:

(a)  14

(b)  15

(c)  17

(d) 16

Answer: (d)

10. If  is continuous at x = 0 then a + 2b is equal to:

(a)  −2

(b)  1

(c)  0

(d) −1

Answer: (c)

11. If the matrices  B = adj A and C = 3A, then   is equal to:

(a)  16

(b)  2

(c)  8

(d) 72

Answer: (c)

12. A circle touches the y-axis at the point (0,4) and passes through the point (2,0). Which of the following lines is not a tangent to the circle?

(a)  4x−3y+17 = 0

(b)  3x+4y−6 = 0

(c)  4x+3y−8 = 0

(d) 3x−4y−24 = 0

Answer: (c)

13. Let z be a complex number such that  Then the value of |z + 3i| is:

(a)  √10

(b)  7/2

(c)  15/4

(d) 2√3

Answer: (b)

14. If f′(x) = tan1(sec x + tan x),  and f(0) = 0, then f(1) is equal to:

(a)  (π+1)/4

(b)  (π+2)/4

(c)  1/4

(d) (π−1)/4

Answer: (a)

15. Negation of the statement: ′√5 is an integer or 5 is irrational′ is:

(a)  √5 is irrational or 5 is an integer.

(b)  √5 is not an integer or 5 is not irrational.

(c)  √5 is an integer and 5 is irrational.

(d) √5 is not an integer and 5 is not irrational.

Answer: (d)

16. If for all real triplets (a,b,c), f(x) = a+ bx+ cx2; then  is equal to:

(a) 

(b) 

(c) 

(d) 

Answer: (d)

17. If the number of five digit numbers with distinct digits and 2 at the 10th place is 336k, then k is equal to:

(a)  8

(b)  7

(c)  4

(d) 6

Answer: (a)

18. Let the observations xi(1 ≤ i ≤ 10) satisfy the equations,  and  If μ and λ are the mean and the variance of observations, (x1 – 3), (x2 – 3) …. (x10 – 3), then the ordered pair (μ, λ) is equal to:

(a)  (6, 3)

(b)  (3, 6)

(c)  (3, 3)

(d) (6, 6)

Answer: (c)

19. The integral  is equal to: (where C is a constant of integration)

(a) 

(b) 

(c) 

(d) 

Answer: (c)

20. In a box, there are 20 cards out of which 10 are labelled as A and remaining 10 are labelled as B. Cards are drawn at random, one after the other and with replacement, till a second A-card is obtained. The probability that the second A-card appears before the third B-card is:

(a)  15/16

(b)  9/16

(c)  13/16

(d) 11/16

Answer: (d)

21. If the vectors  and are coplanar and   then value of λ is ______.

Answer: (1)

22. The projection of the line segment joining the points (1,−1,3) and (2,−4,11) on the line joining the points (−1, 2, 3) and (3,−2,10) is _____.

Answer: (8)

23. The number of distinct solutions of the equation  in the interval [0, 2π], is _________.

Answer: (8)

24. If for x ≥ 0,y = y(x) is the solution of the differential equation (1 + x)dy = [(1 + x)2 + y − 3]dx, y(2) = 0, then y(3) is equal to:

Answer: (3)

25. The coefficient of x4 in the expansion of (1 + x + x)10 is

Answer: (615)

JEE Main January 8 2020 Shift 2 Question Paper with Answer Key

Physics

1. A very long wire ABDMNDC is shown in figure carrying current i. AB and BC parts are straight, long and at right angle. At D wire forms a circular turn DMND of radius R. AB, BC are tangential to circular turn at N and D. Magnetic field at the centre of circle is

(a) 

(b) 

(c) 

(d) 

Answer: (d)

2. A particle moves such that its position vector  where ω is a constant and t is time. Then which of the following statements is true for the velocity  and acceleration  of the particle?

(a)   both are perpendicular to 

(b)   both are parallel to 

(c)   is perpendicular to  is directed away from the origin

(d)  is perpendicular to  is directed towards the origin

Answer: (d)

3. Consider two charged metallic sphere S1 and S2 of radii r1 and r2, respectively. The electric fields E1(on S1) and E2(on S2) on their surfaces are such that  Then the ratio V1(on S1)/V2 (on S2) of the electrostatic potential on each sphere is

(a)  r1/r2

(b)  (r1/r2)2

(c)  r2/r1

(d) (r1/r2)3

Answer: (b)

4. A transverse wave travels on a taut steel wire with a velocity of V when tension in it is 2.06 × 104 N. When the tension is changed to T, the velocity changed to V/2. The value of T is close to

(a)  30.5 × 104 N

(b)  2.50 × 104 N

(c)  10.2 × 102 N

(d) 5.15 × 103 N

Answer: (d)

5. A particle of mass m is dropped from a height ℎ above the ground. At the same time another particle of the same mass is thrown vertically upwards from the ground with a speed of √2gh. If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of  is

(a) 

(b) 

(c)  1/2

(d) 

Answer: (a)

6. A Carnot engine having an efficiency of 1/10 is being used as a refrigerator. If the work done on the refrigerator is 10 J, the amount of heat absorbed from the reservoir at lower temperature is

(a)  99 J

(b)  90 J

(c)  1 J

(d) 100 J

Answer: (b)

7. Two liquids of density ρ1 and ρ22 = 2ρ1) are filled up behind a square wall of side 10 𝑚 as shown in figure. Each liquid has a height of 5 𝑚. The ratio of forces due to these liquids exerted on the upper part MN to that at the lower part NO is (Assume that the liquids are not mixing)

(a)  2/3

(b)  1/2

(c)  1/4

(d) 1/3

Answer: ()

8. As shown in figure, when a spherical cavity (centered at O) of radius 1 m is cut out of a uniform sphere of radius 𝑅 (centered at C ), the center of mass of remaining (shaded) part of sphere is shown by COM, i.e. on the surface of the cavity. R can be determined by the equation

(a)  (R2 + R + 1) (2 – R) = 1

(b)  (R2 – R – 1) (2 – R) = 1

(c)  (R2 – R + 1) (2 – R) = 1

(d) (R2 + R – 1) (2 – R) = 1

Answer: (a)

9. A particle of mass m and charge q is released from rest in uniform electric field. If there is no other force on the particle, the dependence of its speed V on the distance x travelled by it is correctly given by (graphs are schematic and not drawn to scale)

Answer: (b)

10. A galvanometer having a coil resistance 100 Ω gives a full scale deflection when a current of 1 mA is passed through it. What is the value of the resistance which can convert this galvanometer into voltmeter giving full scale deflection for a potential difference of 10 V? In full scale deflection, current in galvanometer of resistance is 1 mA. Resistance required in series to convert it into voltmeter of range 10 V.

(a)  7.9 kΩ

(b)  9.9 kΩ

(c)  8.9 kΩ

(d) 10 kΩ

Answer: (b)

11. Consider a mixture of 𝑛 moles of helium gas and 2𝑛 moles of oxygen gas (molecules taken to be rigid) as an ideal gas. Its (Cp/Cv) value will be

(a)  67/45

(b)  40/27

(c)  19/13

(d) 23/15

Answer: (c)

12. A uniform sphere of mass 500 gm rolls without slipping on a plane horizontal surface with its centre moving at a speed of 5 cm/s. Its kinetic energy is

(a)  8.75 × 104 J

(b)  6.25 × 104 J

(c)  8.75 × 103 J

(d) 1.13 × 103 J

Answer: (a)

13. A capacitor is made of two square plates each of side ‘a’ making a very small angle 𝛼 between them, as shown in figure. The capacitance will be close to

(a) 

(b) 

(c) 

(d) 

Answer: (a)

14. In a double-slit experiment, at a certain point on the screen the path difference between the two interfering waves is 1/8th of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is

(a)  0.568

(b)  0.853

(c)  0.672

(d) 0.760

Answer: (b)

15. As shown in figure, a battery of emf ε is connected to an inductor L and resistance R in series. The switch is closed at t = 0. The total charge that flows from the battery, between t = 0 and 𝑡 = tc (tc is the time constant of the circuit) is

(a)  εL/eR2

(b)  εR/eL2

(c) 

(d) εL/R2

Answer: (a)

16. A plane electromagnetic wave of frequency 25 GHz is propagating in vacuum along the z direction. At a particular point in space and time, the magnetic field is given by The corresponding electric field is given by  is (speed of light 𝑐 = 3 × 108 m/s)

(a) 

(b) 

(c) 

(d) 

Answer: (c)

17. An object is gradually moving away from the focal point of a concave mirror along the axis of the mirror. The graphical representation of the magnitude of linear magnification (m) versus distance of the object from the mirror (x) is correctly given by (Graphs are drawn schematically and are not to scale)

Answer: (b)

18. A simple pendulum is being used to determine the value of gravitational acceleration g at a certain place. The length of the pendulum is 25.0 cm and a stop watch with 1 sec resolution measures the time taken for 40 oscillations to be 50 sec. The accuracy in g

(a)  5.40%

(b)  3.40%

(c)  4.40%

(d) 2.4%

Answer: (c)

19. An electron (mass 𝑚) with initial velocity  is an electric field  If λ0 is initial de-Broglie wavelength of electron. its de-Broglie wavelength at time t is given by

(a) 

(b) 

(c) 

(d) 

Answer: (a)

20. In the given circuit, value of Y is

(a)  1

(b)  0

(c)  Will not execute

(d) Toggles between 0 and 1

Answer: (b)

21. The first member of Balmer series of hydrogen atom has a wavelength of 6561 Å. The wavelength of the second member of the Balmer series (in nm) is

Answer: (486 nm)

22. A ball is dropped from the top of a 100 m high tower on a planet. In the last 1/2 s before hitting the ground, it covers a distance of 19 𝑚. Acceleration due to gravity (in ms−2) near the surface on that planet is Solution: g = 8 m/s2

Answer: (8 m/s2)

23. Three containers C1, C2 and C3 have water at different temperatures. The table below shows the final temperature T when different amounts of water (given in liters) are taken from each container and mixed (assume no loss of heat during the process)

C1 C2 C3 T(°C)
1l 2l 60
1l 2l 30
2l 1l 60
1l 1l 1l θ

The value of θ (in °C to the nearest integer) is

Answer: (50)

24. An asteroid is moving directly towards the centre of the earth. When at a distance of 10R (R is the radius of the earth) from the earth’s centre, it has a speed of 12 km/s. Neglecting the effect of earth’s atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is 12 km/s )? Give your answer to the nearest integer in km/s

Answer: (16)

25. The series combination of two batteries both of the same emf 10 V, but different internal resistance of 20 Ω and 5 Ω , is connected to the parallel combination of two resistors 30 Ω and R Ω. The voltage difference across the battery of internal resistance 20 Ω is zero, the value of R (in Ω) is

Answer: (30)

Chemistry

1. Arrange the following bonds according to their average bond energies in descending order:

C-Cl, C-Br, C-F, C-I

(a)  C-Cl > C-Br > C-I > C-F

(b)  C-Br>C-I>C-Cl>C-F

(c)  C-I>C-Br>C-Cl>C-F

(d) C-F>C-Cl>C-Br>C-I

Answer: (d)

2. The radius of second Bohr orbit, in terms of the Bohr radius, 𝑎0 , in Li2+ is:

(a)  2a0/3

(b)  4a0/9

(c)  4a0/3

(d) 2a0/9

Answer: (c)

3. A metal (A) on heating in nitrogen gas gives compound B. B on treatment with H2O gives a colourless gas which when passed through CuSO4 solution gives a dark blue-violet coloured solution. A and B respectively, are :

(a)  Na and Na­3N

(b)  Mg and Mg3N2

(c)  Mg, Mg(NO3)2

(d) Na, NaNO3

Answer: (a)

4. The correct order of the calculated spin-only magnetic moments of complexes A to D is:

(A) Ni(CO)4

(B) [Ni(H2O)6]2+

(C) Na2[Ni(CN)4]

(D) PdCl2(PPh3)2

(a)  (C) < (D) < (B) < (A)

(b)  (A) ≈ (C) ≈ (D) < (B)

(c)  (A) ≈ (C) < (B) ≈ (D)

(d) (C) ≈ (D) < (B) < (A)

Answer: (b)

5. Hydrogen has three isotopes (A), (B) and (C). If the number of neutron(s) in (A), (B) and (C) respectively, are (x), (y) and (z), the sum of (x), (y) and (z) is:

(a)  4

(b)  1

(c)  3

(d) 2

Answer: (c)

6. Consider the following plots of rate constant versus 1/T for four different reactions. Which of the following orders is correct for the activation energies of these reactions?

(a)  Ea > Ec > Ed > Eb

(b)  Ec > Ea > Ed > Eb

(c)  Eb > Ed > Ec > Ea

(d) E > Ea > Ed > Ec

Answer: (b)

7. Which of the following compounds is likely to show both Frenkel and Schottky defects in its crystalline form?

(a)  ZnS

(b)  CsCl

(c)  KBr

(d) AgBr

Answer: (d)

8. White phosphorus on reaction with concentrated NaOH solution in an inert atmosphere of CO2 gives phosphine and compound (X). (X) on acidification with HCl gives compound (Y). The basicity of compound (Y) is:

(a)  4

(b)  2

(c)  3

(d) 1

Answer: (d)

9. Among the reactions (a) – (d), the reaction(s) that does/do not occur in the blast furnace during the extraction of iron is/are:

(A) CaO + SiO2 → CaSiO3

(B) 3Fe2O3 + CO → 2Fe3O4 + CO2

(C) FeO + SiO2 → FeSiO3

(d) FeO → Fe + (1/2)O2

(a)  A

(b)  D

(c)  C and D

(d) A and D

Answer: (c)

10. The increasing order of the atomic radii of the following elements is:

(A) C

(B) O

(C) F

(D) Cl

(E) Br

(a)  B<C<D<A<E

(b)  C<B<A<D<E

(c)  A<B<C<D<E

(d) D<C<B<A<E l

Answer: (a)

11. Among (a) – (d), the complexes that can display geometrical isomerism are:

(A) [Pt(NH3)3Cl]+

(B) [Pt(NH3)Cl5]

(C) [Pt(NH3)2Cl(NO2)]

(D) [Pt(NH3)4ClBr]2+

(a)  A and B

(b)  D and A

(c)  C and D

(d) B and C

Answer: (a)

12. For the following Assertion and Reason, the correct option is:.

Assertion: The pH of water increases with increase in temperature.

Reason: The dissociation of water into H+ and OH an exothermic reaction.

(a)  Both assertion and reason are false.

(b)  Assertion is not true, but reason is true.

(c)  Both assertion and reason are true and the reason is the correct explanation for the assertion.

(d) Both assertion and reason are true, but the reason is not the correct explanation for the assertion.

Answer: (d)

13. For the following Assertion and Reason, the correct option is:

Assertion: For hydrogenation reactions, the catalytic activity increases from group-5 to group11 metals with maximum activity shown by group 7-9 elements

Reason: The reactants are most strongly adsorbed on group 7-9 elements

(a)  Both assertion and reason are false.

(b)  The assertion is true, but the reason is false.

(c)  Both assertion and reason are true, but the reason is not the correct explanation of assertion

(d) Both assertion and reason are true and the reason is the correct explanation of assertion

Answer: (a)

14. The major product of the following reactions is:

Answer: (d)

15. Find The major product [B] of the following sequence of reactions is:

Answer: (c)

16. Among the following compounds A and B with molecular formula C9H18O3, A is having higher boiling point than B. The possible structures of A and B are

Answer: (b)

17. Kjeldahl’s method cannot be used to estimate nitrogen for which of the following compounds?

(a)  CH3CH2 – C = N

(b)  C6H5NH2

(c)  C6H5NO2

(d) 

Answer: (c)

18. An unsaturated hydrocarbon absorbs two hydrogen molecules on catalytic hydrogenation, and also gives following reaction;  X will be:

Answer: (b)

19. Preparation of Bakelite proceeds via reactions:

(a)  Electrophilic substitution and dehydration.

(b)  Electrophilic addition and dehydration.

(c)  Condensation and elimination

(d) Nucleophilic addition and dehydration

Answer: (a)

20. Two monomers of maltose are:

(a)  alpha-D-Glucose and alpha-D-Galactose

(b)  alpha-D-Glucose and alpha-D-Glucose

(c)  alpha-D-Glucose and alpha-D-Fructose

(d) alpha-D-Glucose and alpha-D-Glucose

Answer: (b)

21. At constant volume, 4 mol of an ideal gas when heated from 300 K to 500 K changes its internal energy by 5000 J. The molar heat capacity at constant volume is _____.

Answer: (6.25)

22. For an electrochemical cell

Sn(s)[Sn2+(aq., 1M) ||Pb2+(aq., 1M)|Pb(s)

The ratio[Sn2+]/[Pb2+] when this cell attains equilibrium is________.

 

Answer: (2.15)

23. NaClO3 is used, even in spacecrafts, to produce O2. The daily consumption of pure O2 by a person is 492 L at 1 atm, 300 K. How much amount of NaClO3, in grams, is required to produce O2 for the daily consumption of a person at 1 atm, 300 K ?

NaClO3(s) + Fe(s) → O2(g) + FeO(s) + NaCl(s)

R = 0.082 L atm mol1 K1

Answer: (2.13)

24. Complexes [ML5] of metals Ni and Fe have ideal square pyramidal and trigonal bipyramidal and geometries, respectively. The sum of the 900, 1200 and 1800 L-M-L angles in the two complexes is ______.

Answer: (20)

25. In the following sequence of reactions, the maximum number of atoms present in molecule ‘C’ in one plane is _____

(Where A is a lowest molecular weight alkyne).

Answer: (13)

Mathematics

1. Let A and B be two events such that the probability that exactly one of them occurs is 2/5 and the probability that A or B occurs is 1/2, then the probability of both of them occur together is

(a)  0.10

(b)  0.20

(c)  0.01

(d) 0.02

Answer: (a)

2. Let 𝑆 be the set of all real roots of the equation, 3x (3x − 1) + 2 = |3x − 1| + |3x − 2|. Then S:

(a)  is a singleton.

(b)  is an empty set.

(c)  contains at least four elements

(d) contains exactly two elements.

Answer: (a)

3. The mean and variance of 20 observations are found to be 10 and 4, respectively. On rechecking, it was found that an observation 9 was incorrect and the correct observation was 11. Then the correct variance is:

(a)  4.01

(b)  3.99

(c)  3.98

(d) 4.02

Answer: (b)

4. Let  be two vectors. If  is a vector such that  is equal to:

(a)  1/2

(b)  −3/2

(c)  −1/2

(d) −1

Answer: (c)

5. Let f: (1,3) → 𝑅 be a function defined by f(x) = x[x]/(x2 +1) , where [x] denotes the greatest integer ≤ x. Then the range of 𝑓 is:

(a)  (2/5 , 3/5 ] ∪ ( 3/4 , 4/5 )

(b)  (2/5 , 4/5 ]

(c)  (3/5 , 4/5 )

(d) (2/5 , 1/2 ) ∪ ( 3/5 , 4/5 ]

Answer: (d)

6. If α and β be the coefficients of x4 and x2 respectively in the expansion of  then:

(a)  α + β = −30

(b)  α − β = −132

(c)  α + β = 60

(d) α − β = 60

Answer: (b)

7. If a hyperbola passes through the point (10, 16) and it has vertices at (±6, 0), then the equation of the normal at P is:

(a)  3x + 4y = 94

(b)  x + 2y = 42

(c)  2x + 5y = 100

(d) x + 3y = 58

Answer: (c)

8. is equal to:

(a)  0

(b)  1/10

(c)  −1/10

(d) −1/5

Answer: (a)

9. If a line, y = mx + c is a tangent to the circle, (x − 3)2 + y2 = 1 and it is perpendicular to a line L1, where L1 is the tangent to the circle, x2 + y2 = 1 at the point ( 1 /√2 , 1/√2 ); then:

(a)  c2 + 7c+ 6 = 0

(b)  c2 – 6c + 7 = 0

(c)  c2 – 7c + 6 = 0

(d) c2 + 6c + 7 = 0

Answer: (d)

10. Let  If  then a and b are the roots of the quadratic equation:

(a)  x2 + 101x + 100 = 0

(b)  x2 + 102x + 101 = 0

(c)  x2 – 102x + 101 = 0

(d) x2 – 101x + 100 = 0

Answer: (c)

11. The mirror image of the point (1, 2, 3) in a plane is  Which of the following points lies on  this plane?

(a)  (1, −1, 1)

(b)  (−1, −1, 1)

(c)  (1, 1, 1)

(d) (−1, −1, −1)

Answer: (a)

12. The length of the perpendicular from the origin, on the normal to the curve, x2 + 2xy – 3y2 = 0 at the point (2, 2) is:

(a)  2

(b)  2√2

(c)  4√2

(d) √2

Answer: (b)

13. Which of the following statements is a tautology?

(a)  ~(p ∧ ~q) → (p ∨ q)

(b)  (~p ∨ ~q) → (p ∧ q)

(c)  p ∨ (~q) → (p ∧ q)

(d) ~(p ∨ ~q) → (p ∨ q)

Answer: (d)

14. If  then:

(a)  1/6 < I2 < 1/2

(b)  1/8 < I2 < 1/4

(c)  1/9 < I2 < 1/8

(d) 1/16 < I2 < 1/9

Answer: (c)

15. If  then 10A1 is equal to:

(a)  6I – A

(b)  A – 6I

(c)  4I – A

(d) A – 4I

Answer: (b)

16. The area (in sq. units) of the region {(x, y) ∈ R2 : x2 ≤ y ≤ 3 – 2x}, is:

(a)  31/3

(b)  32/3

(c)  29/3

(d) 34/3

Answer: (b)

17. Let S be the set of all functions f : [0,1] →R, which are continuous on [0, 1] and differentiable on (0, 1). Then for every f in 𝑆, there exists a c ∈ (0,1), depending on f, such that:

(a) 

(b)  |f(c) + f(1)| < |f′(c)|

(c)  |f(c) + f(1)| < (1 + c)|f′(c)|

(d) |f(c) − f(1)| < (1 − c)|f′(c)|

Answer: (*)

18. The differential equation of the family of curves, x2 = 4b(y + b), b ∈ R, is:

(a)  xy′′ = y′

(b)  x(y′)2 = x + 2yy′

(c)  x(y′)2 = x – 2yy′

(d) x(y′)2 = 2yy′ − x

Answer: (b)

19. The system of linear equations

λx + 2y + 2z = 5

2λx + 3y + 5z = 8

4x + λy + 6z = 10 has:

(a)  no solution when λ = 2

(b)  infinitely many solutions when λ = 2

(c)  no solution when λ = 8

(d) a unique solution when λ = −8

Answer: (a)

20. If the 10th term of an A.P. is 1/20 and its 20𝑡ℎ term is 1/10 , then the sum of its first 200 terms is:

(a) 

(b)  100

(c)  50

(d) 

Answer: (d)

21. Let a line y = mx (m > 0) intersect the parabola, y2 = x at a point 𝑃, other than the origin. Let the tangent to it at 𝑃 meet the x−axis at the point Q. If area (ΔOPQ) = 4 sq. units, then 𝑚 is equal to __________ .

Answer: (0.5)

22. Let f(𝑥) be a polynomial of degree 3 such that f(−1) = 10, f(1) = −6, f(x) has a critical point at 𝑥 = −1 and f′(𝑥) has a critical point at x = 1. Then the local minima at x =______

Answer: (3)

23. If    then tan(α + 2β) is equal to_______.

Answer: (1)

24. The number of 4 letter words (with or without meaning) that can be made from the eleven letters of the word “EXAMINATION” is _________.

Answer: (2454)

25. The sum,  is equal to ________.

Answer: (504)

JEE Main January 8 2020 Shift 1 Question Paper with Answer Key

Physics

1. A particle of mass m is fixed to one end of a light spring having force constant k and ustreatch length l. The other end is fixed. The system is given an angular speed ω about the fixed end of the spring such that it rotates in a circle in gravity free space. Then the stretch in the spring is

(a) 

(b) 

(c) 

(d) 

Answer: (a)

2. Three charged particles A, B and C, with charge −4q, +2q and −2q present on the circumference of a circle of radius d. The charges particles A, C and centre O of the circle formed an equilateral triangle as shown in figure. Electric field at O along x-direction is:

(a) 

(b) 

(c) 

(d) 

Answer: (c)

3. A thermodynamic cycle xyzx is shown on a V – T diagram.

The P-V diagram that best describes this cycle is : (Diagrams are schematic and not upto scale)

Answer: (c)

4. Find the co-ordinates of center of mass of the lamina shown in the figure below.

(a)  (0.75 m, 1.75 m)

(b)  (0.075 m, 0.75 m)

(c)  (1.25 m, 1.5 m)

(d) (1 m, 1.75 m)

Answer: (a)

5. The plot that depicts the behavior of the mean free time τ (time between two successive collisions) fot the molecules of an ideal gas, as a function of temperature (T), qualitatively, is: (Graph the schematic and not drawn to scale)

Answer: (a)

6. Effective capacitance of parallel combination of two capacitors C1 and C2 is 10 μF. When these capacitor are individually connects to a voltage source of 1 V, the energy stored in the capacitor C2 is 4 times of that in C1. If these capacitors are connected in series, their effective capacitance will be:

(a)  1.6 μF

(b)  3.2 μF

(c)  4.2 μF

(d) 8.4 μF

Answer: (a)

7. Consider a uniform rod of mass 4m and length L pivoted about its centre. A mass m is moving with a velocity ν making angle θ=π/4 to the rod’s long axis collides with one end of the rod and stick to it. The angular speed of the rod-mass system just after collision is

(a) 

(b) 

(c) 

(d) 

Answer: (a)

8. When photons of energy 4 eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TA eV and de-Broglie wavelength λA. The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50 eV is TB = (TA − 1.5) eV. If the de-Broglie wavelength of these photoelectrons λB = 2 λA, then the work function of metal B is

(a)  3 eV

(b)  1.5 eV

(c)  2 eV

(d) 4 eV

Answer: (d)

9. The length of a potentiometer wire of length 1200 𝑐𝑚 and it carries a current of 60 mA. For a cell of emf 5 V and internal resistance of 20 Ω, the null point on it is found to be at 1000 cm. The resistance of whole wire is

(a)  80 Ω

(b)  100 Ω

(c)  120 Ω

(d) 60 Ω

Answer: (b)

10. The magnifying power of a telescope with tube length 60 cm is 5. What is the focal length of its eyepiece?

(a)  10 cm

(b)  20 cm

(c)  30 cm

(d) 40 cm

Answer: (a)

11. Consider two solid spheres of radii R1 = 1 m, R2 = 2 m and masses M1 & M2, respectively. The gravitational field due to two spheres 1 and 2 are shown. The value of M1/M2 is

(a)  1/6

(b)  1/3

(c)  1/2

(d) 2/3

Answer: (a)

12. Proton with kinetic energy of 1 MeV moves from south to north. It gets an acceleration of 1012 m/s2 by an applied magnetic field (west to east). The value of magnetic field: (Rest mass of proton is 1.6 × 10−27 kg)

(a)  0.71 mT

(b)  7.1 mT

(c)  71 mT

(d) 0.071 mT

Answer: (a)

13. If finding the electric field around a surface is given by  is applicable. In the formula Ɛ0 is permittivity of free space, A is area of Gaussian and qenc is charge enclosed by the Gaussian surface. This equation can be used in which of the following equation?

(a)  Only when the Gaussian surface is an equipotential surface.

(b)  Only when  = constant on the surface.

(c)  Equipotential surface and  is constant on the surface

(d) for any choice of Gaussian surfaces.

Answer: (c)

14. The dimension of stopping potential V0 in photoelectric effect in units of Planck’s constant (h), speed of light (c), and gravitational constant (G) and Ampere (A) is

(a)  h2/3c5/3G1/3A−1

(b)  h2c1/3G3/2A−1

(c)  h1/3G2/3c1/3A−1

(d) h−2/3c−1/3G4/3A−1

Answer: (*)

15. A leak proof cylinder of length 1 m, made of metal which has very low coefficient of expansion is floating in water at 0°C such that its height above the water surface is 20 cm. When the temperature of water is increases to 4°C, the height of the cylinder above the water surface becomes 21 cm. The density of water at T = 4°C relative to the density at T = 0°C is close to

(a)  1.01

(b)  1.03

(c)  1.26

(d) 1.04

Answer: (a)

16. The graph which depicts the result of Rutherford gold foil experiment with α- particle is:

θ: Scattering angle

N : Number of scattered α – particles is detected

(Plots are schematic and not to scale)

Answer: (b)

17. At time t = 0 magnetic field of 1000 Gauss is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to 500 Gauss, in the next 5 s, then induced EMF in the loop is:

(a)  56 μV

(b)  28 μV

(c)  30 μV

(d) 48 μV

Answer: (a)

18. Choose the correct Boolean expression for the given circuit diagram:

(a)  A.B

(b) 

(c)  A + B

(d) 

Answer: (d)

19. Consider a solid sphere of density  The minimum density of a liquid in which it float is just

(a) 

(b) 

(c)  ρ0/5

(d) ρ0/3

Answer: (a)

20. The critical angle of a medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability 4/3 for this wavelength, will be

(a)  15°

(b)  30°

(c)  45°

(d) 60°

Answer: (b)

21. A body of mass m = 10 kg has an initial velocity of  It collides elastically with another body, B of the mass which has an initial velocity of  After collision, A moves with a velocity  The energy of B after collision is written as (x/10) J, the value of x is

Answer: (1)

22. A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is 30 cm and the refractive index of lens material is 1.5, then the focal length of the lens (in cm) is

Answer: (60 cm)

23. A particle is moving along the x-axis with its coordinate with time t given by x(t) = -3t2 + 8t + 10 m. Another particle is moving along the y-axis with its coordinate as a function of time given by y = 5 – 8t3 At t = 1 s, the speed of the second particle as measured in the frame of the first particle is given as √v . Then v (m/s) is

Answer: (580 m/s)

24. A one metre long (both ends open) organ pipe is kept in a gas that has double the density of air at STP. Assuming the speed of sound in air at STP is 300 m/s, the frequency difference between the fundamental and second harmonic of this pipe is ____Hz.

Answer: (106.05 Hz)

25. Four resistors of resistance 15 Ω, 12 Ω, 4Ω and 10Ω respectively in cyclic order to form a wheatstone’s network. The resistance that is to be connected in parallel with the resistance of 10 to balance the network is _______.

Answer: (10 Ω)

Chemistry

1. The number of bonds between sulphur and oxygen atoms in S2O82− and number of bonds between sulphur and sulphur atoms in rhombic sulphur, respectively, are:

(a)  8 and 6

(b)  4 and 6

(c)  8 and 8

(d) 4 and 8

Answer: (c)

2. The predominant intermolecular forces present in ethyl acetate, a liquid, are:

(a)  London dispersion, dipole-dipole and hydrogen bonding

(b)  hydrogen bonding and London dispersion

(c)  dipole-dipole and hydrogen bonding

(d) London dispersion and dipole-dipole

Answer: (d)

3. For the Balmer series in the spectrum of H-atom,

The correct statements among (A) to (D) are:

(A) The integer n1 = 2.

(B) The ionization energy of hydrogen can be calculated from the wave number of these lines.

(C) The lines of longest wavelength corresponds to n2= 3.

(D) As wavelength decreases, the lines of the series converge.

(a)  B, C, D

(b)  A, B, D

(c)  A, C, D

(d) A, B, C

Answer: (c)

4. The first ionization energy (in kJ/mol) of Na, Mg, Al and Si, respectively,

(a)  496, 737, 577, 786

(b)  496, 577, 737, 786

(c)  496, 577, 786, 737

(d) 786, 737, 577, 496

Answer: (a)

5. The stoichiometry and solubility product of a salt with the solubility curve given below is, respectively:

(a)  X2Y, 2 × 10−9M3

(b)  XY2, 1 × 10−9 M3

(c)  XY2, 4 × 10−9 M3

(d) XY, 2 × 10−6 M3

Answer: (c)

6. The complex that can show fac- and mer-isomers is:

(a)  [Co(NO2)3(NH3)3]

(b)  [PtCl2(NH3)2

(c)  [Co(NH3)4Cl2]

(d) [CoCl2(en)2]

Answer: (a)

7. A graph of vapour pressure and temperature for three different liquids X, Y and Z is shown below:

The following inferences are made:

(A) X has higher intermolecular interactions compared to Y

(B) X has lower intermolecular interactions compared to Y

(C) Z has lower intermolecular interactions compared to Y

The correct inference(s) is/are:

(a)  C

(b)  A

(c)  B

(d) A and C

Answer: (c)

8. As per Hardy-Schulze formulation, the flocculation values of the following for ferric hydroxide sol are in the order:

(a)  AlCl3 > K3[Fe(CN)6] > K2CrO4 > KBr = KNO3

(b)  K3 [Fe(CN)6 ] < K2CrO4 < AlCl3 < KBr < KNO3

(c)  K3 [Fe(CN)6 ] < K2CrO4 < KBr = KNO3 = AlCl3

(d) K3 [Fe(CN)6 ] > AlCl3 > K2CrO4 > KBr > KNO3

Answer: (c)

9. The rate of a certain biochemical reaction at physiological temperature (T) occurs 106 times faster with enzyme than without. The change in activation energy upon adding enzyme is:

(a)  − 6RT

(b)  – 6 × 2.303 RT

(c)  + 6RT

(d) +6 × 2.303 RT

Answer: (b)

10. When gypsum is heated to 393K, it forms:

(a) 

(b)  Dead burnt plaster

(c)  CaSO4 ∙ 5H2O

(d) Anhydrous CaSO4

Answer: (a)

11. The third ionization enthalpy is minimum for:

(a)  Mn

(b)  Co

(c)  Ni

(d) Fe

Answer: (d)

12. The strength of an aqueous NaOH solution is most accurately determined by titrating: (Note: consider that an appropriate indicator is used)

(a)  Aq. NaOH in a pipette and aqueous oxalic acid in a burette

(b)  Aq. NaOH in a volumetric flask and concentrated H2SO4 in a conical flask

(c)  Aq. NaOH in a burette and concentrated H2SO4 in a conical flask

(d) Aq. NaOH in a burette and aqueous oxalic acid in a conical flask

Answer: (d)

13. The decreasing order of reactivity towards dehydrohalogenation (E1) reaction of the following compounds is:

(a)  B > A > D > C

(b)  B > D > C > A

(c)  B > D > A > C

(d) D > B > C > A

Answer: (d)

14. Major product in the following reaction is:

Answer: (c)

15. Arrange the following compounds in increasing order of C—OH bond length: methanol, phenol, p-ethoxyphenol

(a)  Phenol < methanol < p-ethoxyphenol

(b)  methanol < p-ethoxyphenol < phenol

(c)  Phenol < p-ethoxyphenol < methanol

(d) methanol < phenol < p-ethoxypheno

Answer: (c)

16. Among the gases (i) – (v), the gases that cause greenhouse effect are:

(i) CO2

(ii) H2O

(iii) CFC

(iv) O2

(v) O3

(a)  i, ii iii and iv

(b)  i, iii iv and v

(c)  i and iv

(d) i, ii, iii and v

Answer: (d)

17. The major products A and B in the following reactions are:

Answer: (a)

18. A flask contains a mixture of isohexane and 3-methylpentane. One of the liquids boils at 63°C while the other boils at 60°C. What is the best way to separate the two liquids and which one will be distilled out first?

(a)  Fractional distillation, isohexane

(b)  Simple distillation, 3-methylpentane

(c)  Fractional distillation, 3-methylpentane

(d) Simple distillation, isohexane

Answer: (a)

19. Which of the given statement is not true for glucose?

(a)  The pentacetate glucose does not react with hydroxylamine to give oxime.

(b)  Glucose reacts with hydroxylamine to form oxime.

(c)  Glucose gives Schiff’s test for aldehyde.

(d) Glucose exists in two crystalline forms alpha and beta.

Answer: (c)

20. The reagent used for the given conversion is:

(a)  B2H6

(b)  LiAlH4

(c)  NaBH4

(d) H2, Pd

Answer: (a)

21. The volume (in mL) of 0.125 M AgNO3 required to quantitatively precipitate chloride ions in 0.3 g of [Co(NH3)6]Cl3­ is______.

Answer: (26.92)

22. What will be the electrode potential for the given half cell reaction at pH= 5?

2H2O → O2 + 4H+ + 4e; E° = −1.23 V

(R = 8.314 Jmol1K1; temp. = 298 K; oxygen under std. atm. pressure of 1 bar.)

Answer: (1.52)

23. Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve 10 ppm of iron in 100 kg of wheat is _______. Atomic weight: Fe=55.85; S=32.00; O=16.00)

Answer: (4.96)

24. The magnitude of work done by gas that undergoes a reversible expansion along the path ABC shown in figure is

Answer: (48)

25. The number of chiral centres in Penicillin is _______.

Answer: (3)

Mathematics

1. For which of the following ordered pairs (μ, δ), the system of linear equations

x + 2y + 3z = 1

3x + 4y + 5z = μ

4x + 4y + 4z = δ

is inconsistent?

(a)  (4, 6)

(b)  (3, 4)

(c)  (1, 0)

(d) (4, 3)

Answer: (d)

2. Let y = (x) be a solution of the differential equation,  |x| < 1. If  is equal to:

(a)  −1/√2

(b)  −√3/2

(c)  1/√2

(d) √3/2

Answer: (c)

3. If a, b and c are the greatest values of 19Cp, 20Cq, 21Cr respectively, then:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

4. Which of the following is a tautology?

(a)  (P ∧ (P → Q)) → Q

(b)  P ∧ (P ∨ Q)

(c)  (Q → (P ∧ (P → Q))

(d) P ∨ (P ∧ Q)

Answer: (a)

5. Let f: R → R be such that for all x ∈ R, (21+x + 21 – x), f(x) and (3x + 3x) are in A.P., then the minimum value of f(x) is:

(a)  0

(b)  4

(c)  3

(d) 2

Answer: (c)

6. The locus of a point which divides the line segment joining the point (0, −1) and a point on the parabola, x2 = 4y, internally in the ratio 1: 2, is:

(a)  9x2 – 12y = 8

(b)  4x2 – 3y = 2

(c)  x2 – 3y = 2

(d) 9x2 – 3y = 2

Answer: (a)

7. For 𝑎 > 0, let the curves C1: y2 = ax and C2 ∶ x2 = ay intersect at origin O and a point 𝑃. Let the line x = b (0 < b < a) intersect the chord OP and the x-axis at points Q and R, respectively. If the line x = b bisects the area bounded by the curves, C1 and C2, and the area of ΔOQR = 1/2,then‘a’ satisfies the equation

(a)  x6 – 12x3 + 4 = 0

(b)  x6 – 12x3 – 4 = 0

(c)  x6 + 6x3 – 4 = 0

(d) x6 – 6x3 + 4 = 0

Answer: (a)

8. The inverse function of  is

(a) 

(b) 

(c) 

(d) 

Answer: (b)

9. 

(a)  e

(b)  1/e2

(c)  1/e

(d) e2

Answer: (b)

10. Let f(x) = (sin(tan1x) + sin(cot1 x))2 – 1, where |x| > 1. If  and y(√3) = π/6, then y(−√3) is equal to:

(a)  π/3

(b)  2π/3

(c)  −π/6

(d) 5π/6

Answer: (*)

11. If the equation, x2 + bx + 45 = 0 (b ∈ R) has conjugate complex roots and they satisfy |z + 1| = 2√10, then :

(a)  b2 + b = 12

(b)  b2 – b = 42

(c)  b2 – b = 30

(d) b2 + b = 72

Answer: (c)

12. The mean and standard deviation (s.d.) of 10 observations are 20 and 2 respectively. Each of these 10 observations is multiplied by p and then reduced by q, where p ≠ 0 and q ≠ If the new mean and standard deviation become half of their original values, then q is equal to:

(a)  −20

(b)  −5

(c)  10

(d) −10

Answer: (a)

13. If  where c is a constant of integration, then λf(π/3) is equal to :

(a)  −9/8

(b)  9/8

(c)  2

(d) −2

Answer: (d)

14. Let A and B be two independent events such that p(A) = 1/3 and P(B) = 1/6. Then which of the following is TRUE?

(a)  P(A/(A ∪ B)) = 1/4

(b)  P(A/B′) = 1/3

(c)  P(A/B) = 2/3

(d) P(A′/B′) = 1/3

Answer: (b)

15. If volume of parallelepiped whose coterminous edges are given by  be 1 cu. unit. If θ be the angle between the edges  then cos θ can be:

(a)  7/6√6

(b)  5/7

(c)  7/6√3

(d) 5/3√3

Answer: (c)

16. Let two points be A(1, −1) and B(0, 2). If a point P(x′, y′) be such that the area of ∆PAB = 5 sq. units and it lies on the line, 3x + y = 4λ = 0. then the value of λ is:

(a)  4

(b)  1

(c)  −3

(d) 3

Answer: (d)

17. The shortest distance between the lines

(a)  2√30

(b) 

(c)  3

(d) 3√30

Answer: (d)

18. Let the line y = mx and the ellipse 2x2 + y2 = 1 intersect a point P in the first quadrant. If the normal to this ellipse at P meets the co-ordinate axes at(−1/3√2, 0) and (0, β), then β is equal to:

(a)  2/√3

(b)  2/3

(c)  2√2/3

(d) √2/3

Answer: (d)

19. If c is a point at which Rolle’s theorem holds for the function,  in the interval [3, 4], where a ∈ R, then f′′(c) is equal to:

(a)  −1/24

(b)  −1/12

(c)  √3/7

(d) 1/12

Answer: (d)

20. Let f(x) = x cos1(sin|−|x|)), x ∈ (−π/2, π/2), then which of the following is true?

(a)  f′(0) = −π/2

(b)  f′ is decreasing in (−π/2, 0) and increasing in (0, π/2)

(c)  f is not differentiable at x = 0

(d) f′ is increasing in (−π/2, 0) and decreasing in (0, π/2)

Answer: (b)

21. An urn contains 5 red marbles, 4 black marbles and 3 white marbles. Then the number of ways in which 4 marbles can be drawn so that at most three of them are red is.

Answer: (490)

22. Let the normal at a P on the curve y2 – 3x2 + y + 10 = 0 intersect the y-axis at (0,3/2). If m is the slope of the tangent at P to the curve, then |m| is equal to____________.

Answer: (4)

23. The least positive value of ‘a’ for which the equation,  has real roots is _______.

Answer: (8)

24. The sum  is _______.

Answer: (1540)

25. The number of all 3×3 matrices A, with entries from the set {−1,0,1} such that the sum of the diagonal elements of (AAT) is 3, is __________.

Answer: (672)

JEE Main January 7 2020 Shift 2 Question Paper with Answer Key

Physics

1. A box weighs 196 N on a spring balance at the North Pole. Its weight recorded on the same balance if it is shifted to the equator is close to (Take g = 10 m/s2 at the North Pole and radius of the Earth = 6400 km)

(a)  194.32 N

(b)  194.66 N

(c)  195.32 N

(d) 195.66 N

Answer: (c)

2. In a building, there are 15 bulbs of 45 w, 15 bulbs of 100 W, 15 small fans of 10 W and 2 heaters of 1 kW. The voltage of electric main is 220 V. The minimum fuse capacity (rated value) of the building will be approximately

(a)  10 A

(b)  20 A

(c)  25 A

(d) 15 A

Answer: (b)

3. Under a adiabatic process, the volume of an ideal gas gets doubled. Consequently, the mean collision time between the gas molecules changes from τ1 to τ2. If  is given by

(a)  1/2

(b) 

(c)  (1/2)γ

(d) 2

Answer: (*)

4. A mass of 10 kg is suspended by a rope of length 4 m, from the ceiling. A force F is applied horizontally at the mid-point of the role such that the top half of the rope makes an angle of 45° with the vertical. Then F equals (Take g = 10 m/s2 and rope to be massless)

(a)  100 N

(b)  90 N

(c)  75 N

(d) 70 N

Answer: (a)

5. Mass per unit area of a circular disc of radius a depends on the distance r from its centre as σ(r) = A + Br. The moment of inertia of the disc about the axis, perpendicular to the plane and passing through its centre is

(a) 

(b) 

(c) 

(d) 

Answer: (a)

6. Two ideal Carnot engines operate in cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures T­1 and T2. The temperature of the hot reservoir of the first engine is T1 and the temperature of the cold reservoir of the second engine is T­2. T is the temperature of the sink of first engine which is also the source for the second engine. How is T related to T1 and T2 if both the engines perform equal amount of work?

(a) 

(b) 

(c)  T = 0

(d) 

Answer: (b)

7. The acitivity of a radioactive substance falls from 700 s1 to 500 s1 in 30 minutes. Its half-life is close to

(a)  66 min

(b)  62 min

(c)  52 min

(d) 72 min

Answer: (b)

8. In a Young’s double slit experiment, the separation between the slits is 0.15 mm. In the experiment, a source of light of wavelength 589 nm is used and the interference pattern is observed on a screen kept 1.5 m away. The separation between the successive bright fringes on the screen is

(a)  5.9 mm

(b)  3.9 mm

(c)  6.9 mm

(d) 4.9 mm

Answer: (a)

9. An ideal fluid flows (laminar flow) through a pipe of non-uniform diameter. The maximum and minimum diameters of the pipes are 6.4 cm and 4.8 cm, respectively. The ratio of minimum and maximum velocities of fluid in this pipe is

(a) 

(b)  9/16

(c)  3/4

(d) 4/3

Answer: (b)

10. In the figure, potential difference between a and b is

(a)  0 V

(b)  15 V

(c)  10 V

(d) 5 V

Answer: (c)

11. A particle of mass m and charge q has an initial velocity  If an electric field and magnetic field   act on the particle, its speed will double after a time

(a) 

(b) 

(c) 

(d) 

Answer: (a)

12. A stationary observer receives sound from two identical tuning forks, one of which approaches and the other one receded with the same speed (much less than the speed of sound). The observer hears 2 beats/sec. The oscillation frequency of each tuning fork is υ0 = 1400 Hz and the velocity of sound in air is 350 m/s. The speed of each tuning fork is close to

(a)  1/4 m/s

(b)  1 m/s

(c)  1/2 m/s

(d) 1/8 m/s

Answer: (a)

13. An electron (of mass m) and a photon have the same energy E in the range of few eV. The ratio of the de Broglie wavelength associated with the electron and the wavelength of the photon is. (c = speed of light in vacuum)

(a)  (E/2m)1/2

(b)  1/c(2E/m)1/2

(c)  c(2mE)1/2

(d) 1/c(E/2m)1/2

Answer: (d)

14. A planar loop of wire rotates in a uniform magnetic field. Initially at t = 0, the plane of the loop is perpendicular to the magnetic field. If it rotates with a period of 10 s about an axis in its plane, then the magnitude of induced emf will be maximum and minimum, respectively at

(a)  2.5 sec and 5 sec

(b)  5 sec and 7.5 sec

(c)  2.5 sec and 7.5 sec

(d) 5 sec and 10 sec

Answer: (a)

15. The electric field of a plane electromagnetic wave is given by At t = 0, a positively charged particle is at the point (x, y, z) = (0, 0, π/k). If its instantaneous velocity at t = 0 is  the force acting on it due to the wave is

(a)  zero

(b) 

(c) 

(d) 

Answer: (b)

16. A thin lens made of glass (refractive index = 1.5) of focal length f =16 cm is immersed in a liquid of refractive index 1.42. If its focal length in liquid is fl, then the ratio fl/f is closest to the integer

(a)  9

(b)  17

(c)  1

(d) 5

Answer: (a)

17. An elevator in a building can carry a maximum of 10 persons, with the average mass of each person being 68 kg. The mass of the elevator itself is 920 kg and it moves with a constant speed of 3 m/s. The frictional force opposing the motion is 6000 N. If the elevator is moving up with its full capacity, the power delivered by the motor to the elevator (g = 10 m/s2) must be at least

(a)  66000 W

(b)  63360 W

(c)  48000 W

(d) 56300 W

Answer: (a)

18. The figure gives experimentally measured B vs H variation in a ferromagnetic material. The retentivity, coercivity and saturation, respectively, of the material are

(a)  1.5 T, 50 A/m, 1 T

(b)  1 T, 50 A/m, 1.5 T

(c)  1.5 T, 50 A/m, 1 T

(d) 150 A/m, 1 T, 1.5 T

Answer: (b)

19. An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and 5 Ω The ratio of the currents at time t = ∞ and t = 40 s is close to (take e2 = 7.389)

(a)  1.06

(b)  1.46

(c)  1.15

(d) 0.84

Answer: (a)

20. The dimension of B2/2μ0, where B is magnetic field and μ0 is the magnetic permeability of vacuum, is

(a)  ML1T2

(b)  ML2T2

(c)  MLT2

(d) ML2T1

Answer: (a)

21. A 60 pF capacitor is fully charged by a 20 V supply. It is then disconnected from the supply and is connected to another uncharged 60 pF capacitor in parallel. The electrostatic energy that is lost in this process by the time the charge is redistributed between them is (in nJ)______.

Answer: (6)

22. M grams of steam at 100°C is mixed with 200 g of ice at its melting point in a thermally insulated container. If it produces liquid water at 40°C [heat of vaporization of water is 540 cal/g and heat of fusion of ice is 80 cal/g], the value of M is _______.

Answer: (40)

23. Consider a uniform cubical box of side a on a rough floor that is to be moved by applying minimum possible force F at a point b above its centre of mass (see figure). If the coefficient of friction is μ = 0.4, the maximum value of  for the box not to topple before moving is ______.

Answer: (50)

24. The sum of two forces  such that The angle θ (in degrees) that the resultant of   will make with  is_______

Answer: (90°)

25. The balancing length for a cell is 560 cm in a potentiometer experiment. When an external resistance of 10 Ω is connected in parallel to the cell, the balancing length changes by 60 cm. If the internal resistance of the cell is  the value of N is_______

Answer: (12)

Chemistry

1. Consider the following reactions:

Which of these reactions are possible?

(a)  A and D

(b)  B and D

(c)  B, C and D

(d) A and B

Answer: (b)

2. In the following reaction sequence,

The major product B is:

Answer: (a)

3. For the following reactions,

ks and ke, are, respectively, the rate constants for substitution and elimination, and  the correct option is______.

(a)  μA > μB and ke(A) > ke(B)

(b)  μB > μA and ke(A) > ke(B)

(c)  μA > μB and ke(B) > ke(A)

(d) μB > μA and ke(B) > ke(A)

Answer: (c)

4. Which of the following statements is correct?

(a)  Gluconic acid can form cyclic (acetal/hemiacteal) structure

(b)  Gluconic acid is dicarboxylic acid

(c)  Gluconic acid is obtained by oxidation of glucose with HNO3

(d) Gluconic acid is a partial oxidation product of glucose

Answer: (d)

5. The correct order of stability for the following alkoxides is:

(a)  (C) > (A) > (B)

(b)  (B) > (A) > (C)

(c)  (C) > (B) > (A)

(d) (B) > (C) > (A)

Answer: (b)

6. In the following reaction sequence, structures of A and B, respectively will be:

Answer: (a)

7. A chromatography column, packed with silica gel as stationary phase, was used to separate a mixture of compounds consisting of (A) benzanilide, (B) aniline and (C) acetophenone. When the column is eluted with a mixture of solvents, hexane : ethyl acetate (20 : 80), the sequence of obtained compound is:

(a)  (B), (A) and (C)

(b)  (C), (A) and (B)

(c)  (B), (C) and (A)

(d) (A), (B) and (C)

Answer: (b)

8. The number of possible optical isomers for the complexes [MA2B2] with sp3 or dsp2 hybridized metal atom, respectively, is:

Note: A and B are unidentate neutral and unidentate monoanionic ligands, respectively.

(a)  0 and 1

(b)  2 and 2

(c)  0 and 0

(d) 0 and 2

Answer: (b)

9. The bond order and magnetic characteristics of CN are:

(a)  3, paramagnetic

(b)  3, diamagnetic

(c)  2.5, diamagnetic

(d) 2.5, paramagnetic

Answer: (c)

10. The equation that is incorrect is:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

11. In the following reactions, product (A) and (B), respectively, are:

NaOH + Cl2 → (A) + side products

(hot & conc.)

Ca(OH)2 + Cl2 → (B) + side products

(dry)

(a)  NaClO3 and Ca(ClO3)2

(b)  NaOCl and Ca(ClO3)2

(c)  NaOCl and Ca(OCl)2

(d) NaClO3 and Ca(OCl)2

Answer: (d)

12. Two open beakers one containing a solvent and the other containing a mixture of that solvent with a non-volatile solute are together sealed in a container. Over time:

(a)  the volume of the solution and the solvent does not change

(b)  the volume of the solution increases and the volume of the solvent decreases

(c)  the volume of the solution decreases and the volume of the solvent increases

(d) the volume of the solution does not change and the volume of the solvent decreases

Answer: (b)

13. The refining method used when the metal and the impurities have low and high melting temperatures, respectively, is:

(a)  vapour phase refining

(b)  distillation

(c)  liquation

(d) zone refining

Answer: (c)

14. Among statements I-IV, the correct ones are:

(I) Decomposition of hydrogen peroxide gives dioxygen

(II) Like hydrogen peroxide, compounds, such as KClO3, Pb(NO3)2 and NaNO3 when heated liberate dioxygen.

(III) 2-Ethylanthraquinone is useful for the industrial preparation of hydrogen peroxide.

(IV) Hydrogen peroxide is used for the manufacture of sodium perborate

(a)  I, II, III and IV

(b)  I, II and III only

(c)  I, III and IV only

(d) I and III only

Answer: (a)

15. The redox reaction among the following is:

(a)  formation of ozone from atmospheric oxygen in the presence of sunlight

(b)  reaction of H2SO4 with NaOH

(c)  combination of dinitrogen with dioxygen at 2000 K

(d) Reaction of [Co(H2O)6]Cl3 with AgNO3

Answer: (c)

16. Identify the correct labels of A, B and C in the following graph from the options given below:

Root mean square speed (Vrms); most probable speed (Vmp); average speed (Vav)

(a)  A = Vmp, B = Vav, C = Vrms

(b)  A = Vmp, B = Vrms, C = Vav

(c)  A = Vav, B = Vrms, C = Vmp

(d) A = Vrms, B = Vmp, C = Vav

Answer: (a)

17. For the reaction,

2H2(g) + 2NO(g) → N2(g) + 2H2O(g)

The observed rate expression is, rate = kf[NO]2[H2]. The rate expression for the reverse reaction is:

(a)  kb[N2][H2O]2

(b)  kb[N2][H2O]

(c)  kb[N2][H2O]2/[H2]

(d) kb[N2][H2O]2/[NO]

Answer: (c)

18. Within each pair of elements F & Cl, S and Se and Li & Na, respectively, the elements that release more energy upon a electron gain are:

(a)  Cl, Se and Na

(b)  Cl, S and Li

(c)  F, S and Li

(d) F, Se and Na

Answer: (b)

19. Among the following statements A-D, the incorrect ones are:

(A) Octahedral Co(III) complexes with strong field ligands have high magnetic moments

(B) When ∆o < P, the d-electron configuration of Co(III) in an octahedral complex is 

(C) Wavelength of light absorbed by [Co(en)3]3+ is lower than that of [CoF6]3−.

(D) If the ∆o for an octahedral complex of Co(III) is 18000 cm1, the ∆t for its tetrahedral complex with the same ligand will be 1600 cm1.

(a)  B and C only

(b)  A and D only

(c)  A and B only

(d) C and D only

Answer: (c)

20. The ammonia (NH3) released on quantitative reaction of 0.6 g urea (NH2CONH2) with sodium hydroxide (NaOH) can be neutralized by:

(a)  200 mL of 0.2 N HCl

(b)  100 mL of 0.1 N HCl

(c)  200 mL of 0.4 N HCl

(d) 100 mL of 0.2 N HCl

Answer: (d)

21. Number of sp2 hybrid carbon atoms present in aspartame is______.

Answer: (9)

22. 3 grams of acetic acid is added to 250 mL of 0.1 M HCl and the solution is made up to 500 mL. to 20 mL of this solution 1/2 mL of 5 M NaOH is added. The pH of this solution is_______.

(Given: log 3 = 0.4771, pKa of acetic acid = 4.74, molar mass of acetic acid = 60 g/mole).

Answer: (5.22)

23. The flocculation value of HCl for As2S3 sol is 30 mmolL1. If H2SO4 is used for the flocculation of arsenic sulphide, the amount, in grams, of H2SO4 in 250 mL required for the above purpose is _____.

Answer: (0.3675 g)

24. Consider the following reactions:

NaCl + K2Cr2O7 + H2SO4 → (A) + side products

(A) + NaOH → (B) + side products

(B) + H2SO4(dil.) + H2O2 → (C) + side products

The sum of the total number of atoms in one molecule of (A), (B) & (C) is ______.

Answer: (18)

25. The standard heat of formation (∆fH298°) of ethane (in kJ/mol), if the heat of combustion of ethane, hydrogen and graphite are −1560, −393.5 and −286 kJ/mol, respectively, is_______.

Answer: (−192.5 kJ/mol)

Mathematics

1. If 3x + 4y = 12√2 is a tangent to the ellipse  for some a ∈ R then the distance between the foci of the ellipse is:

(a)  2√5

(b)  2√7

(c)  2√2

(d) 4

Answer: (b)

2. Let A, B, C and D be four non-empty sets. The Contrapositive statement of “If A ⊆ B and B ⊆ D then A ⊆ C is :

(a)  If A ⊆ C, then B ⊂ A or D ⊂ B

(b)  If A ⊈ C, then A ⊆ B and B ⊆ D

(c)  If A ⊈ C, then A ⊈ B and B ⊆ D

(d) If A ⊈ C, then A ⊈ B or B ⊈ D

Answer: (d)

3. The coefficient of x7 in the expression (1+ x)10 + x(1 + x)9 + x2(1 + x)8 + … + x10 is :

(a)  420

(b)  330

(c)  210

(d) 120

Answer: (b)

4. In a workshop, there are five machines and the probability of any one of them to be out of service on a day is 1/4. If the probability that at most two machines will be out of service on the same day is (3/4)3k, then k is equal to :

(a)  17/2

(b)  4

(c)  17/4

(d) 17/8

Answer: (d)

5. If locus of mid points of the perpendiculars drawn from points on the line x = 2y to the line x = y is:

(a)  2x – 3y = 0

(b)  3x – 2y = 0

(c)  5x – 7y = 0

(d) 7x – 5y = 0

Answer: (c)

6. The value of α for which  is:

(a)  loge 2

(b)  loge √2

(c)  loge (4/3)

(d) loge (3/2)

Answer: (a)

7. If the sum of the first 40 terms of the series, 3 + 4 + 8 + 9 + 13 + 14 + 18 + 19 + …. is

(a)  10

(b)  25

(c)  5

(d) 20

Answer: (d)

8. If  is a real number, then the argument of sin θ + i cos θ is:

(a)  π − tan1 (4/3)

(b)  −tan1 (3/4)

(c)  π – tan1 (4/3)

(d) tan1 (4/3)

Answer: (a)

9. Let A = [aij] and B = [bij] be two 3 × 3 real matrices such that bij = (3)(i+j2)ji, where i, j = 1, 2, 3. If the determinant of B is 81, then the determinant of A is:

(a)  1/9

(b)  1/81

(c)  1/3

(d) 3

Answer: (c)

10. Let f(x) be a polynomial of degree 5 such that x = ±1 are its critical points. If  then which one of the following is not true?

(a)  f(1) – 4f(−1) = 4

(b)  x = 1 is a point of maxima and x = −1 is a point of minimum of f.

(c)  f is an odd function.

(d) x = 1 is a point of minima and x = −1 is a point of maxima of f.

Answer: (d)

11. The number of ordered pairs (r, k) for which 6 . 35Cr = (k2 – 3) . 36Cr+1, where k is an integer, is:

(a)  4

(b)  6

(c)  2

(d) 3

Answer: (a)

12. Let a1, a2, a3,… be a G.P. such that a1 < 0, a1 + a2 = 4 and a3 + a4 = 16. If 

(a)  171

(b)  511/3

(c)  −171

(d) −513

Answer: (c)

13. Let  be three unit vectors such that   and  then the ordered pair  is equal to:

(a) 

(b) 

(c) 

(d) 

Answer: (c)

14. Let y = y(x) be the solution curve of the differential equation, satisfying y(0) = 1 This curve intersects the x-axis at a point whose abscissa is:

(a)  2 + e

(b)  2

(c)  2 – e

(d) −e

Answer: (c)

15. If θ1 and θ2 be respectively the smallest and the largest values of θ in (0, 2π) – {π} which satisfy the equation, is equal to:

(a)  2π/3

(b)  π/3

(c)  π/3 + 1/6

(d) π/9

Answer: (b)

16. Let α and β are the roots of the equation x2 – x – 1 = 0. If pk = (α)k + (β)k, k ≥ 1 then which one of the following statements is not true?

(a)  (p1 + p2 + p3 + p4 + p5) = 26

(b)  p5 = 11

(c)  p5 = p2 ∙ p3

(d) p3 = p5 – p4

Answer: (c)

17. The area (in sq. units) of the region {(x, y) ϵ R|4x2 ≤ y ≤ 8x + 12} is:

(a)  125/3

(b)  128/3

(c)  124/3

(d) 127/3

Answer: (b)

18. The value of c in Lagrange’s mean value theorem for the function f(x) = x3 – 4x2 + 8x + 11, where x ∈ [0, 1] is:

(a) 

(b)  2/3

(c) 

(d) 

Answer: (a)

19. Let y = y(x) be a function of x satisfying  where k is a constant and  is equal to:

(a)  −√5/2

(b)  √5/2

(c)  −√5/4

(d) 2/√5

Answer: (a)

20. Let the tangents drawn from the origin to the circle, x2 + y2 – 8x – 4y + 16 = 0 touch it at the points A and B. The (AB)2 is equal to:

(a)  32/5

(b)  64/5

(c)  52/5

(d) 56/5

Answer: (b)

21. If system of linear equations

x + y + z = 6

x + 2y + 3z = 10

3x + 2y + λz = μ

has more than two solutions, then μ – λ2 is equal to_______.

Answer: (13)

22. If the foot of perpendicular drawn from the point (1, 0, 3) on a line passing through (α, 7, 1) is (5/3, 7/3, 17/3), then α is equal to________.

Answer: (4)

23. If the function f defined on (−1/3, 1/3) by

is continuous, the k is equal to ______.

Answer: (5)

24. If the mean and variance of eight numbers 3, 7, 9, 12, 13, 20, x and y be 10 and 25 respectively then xy is equal to ________.

Answer: (54)

25. Let X = {n ∈ N: 1 ≤ n ≤ 50}. If A = {n ∈ X: n is a multiple of 2} and B = {n ∈ X : n is a multiple of 7}, then the number of elements in the smallest subset of X containing both A and B is _______.

Answer: (29)

JEE Main January 7 2020 Shift 1 Question Paper with Answer Key

Physics

1. A polarizer-analyzer set is adjusted such that the intensity of light coming out of the analyzer is just 10% of the original intensity. Assuming that the polarizer-analyzer set does not absorb any light, the angle by which the analyzer need to be rotated further to reduce the output intensity to be zero is

(a)  45°

(b)  71.6°

(c)  90°

(d) 18.4°

Answer: (d)

2. Which of the following gives reversible operation?

Answer: (c)

3. A 60 HP electric motor lifts an elevator with a maximum total load capacity of 2000 kg. If the frictional force on the elevator is 4000 N, the speed of the elevator at full load is close to (Given 1 HP = 746 W, g = 10 m/s2)

(a)  1.5 m/s

(b)  2.0 m/s

(c)  1.7 m/s

(d) 1.9 m/s

Answer: (d)

4. A long solenoid of radius R carries a time (t) dependent current I(t) = I0t(1 – t). A ring of radius 2R is placed coaxially near its middle. During the time instant 0 ≤ t ≤ 1, the included current (IR) and the induced EMF (V­R) in the ring changes as:

(a)  Direction of IR remains unchanged and VR is maximum at t = 0.5

(b)  Direction of IR remains unchanged and VR is zero at t = 0.25

(c)  At t = 0.5 direction of IR reverses and VR is zero

(d) At t = 0.25 direction of IR reverse and VR is maximum

Answer: (c)

5. Two moles of an ideal gas with  are  mixed with 3 moles of another ideal gas with The value of   for the mixture is

(a)  1.47

(b)  1.42

(c)  1.45

(d) 1.50

Answer: (b)

6. Consider a circular coil of wire carrying current I, forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by ϕi. The magnetic flux through the area of the circular coil area is given by ϕ Which of the following option is correct?

(a)  ϕi = − ϕ0

(b)  ϕi > ϕ0

(c)  ϕi < ϕ0

(d) ϕi = ϕ0

Answer: (a)

7. The current (i1) (in A) flowing through 1 Ω resistor in the following circuit is

(a)  0.40 A

(b)  0.20 A

(c)  0.25 A

(d) 0.5 A

Answer: (b)

8. Two infinite planes each with uniform surface charge density +σ C/m2 are kept in such a way that the angle between them is 30°. The electric field in the region shown between them is given by:

(a) 

(b) 

(c) 

(d) 

Answer: (a)

9. If the magnetic field in a plane electromagnetic wave is given by  then what will be expression for electric filed?

(a) 

(b) 

(c) 

(d) 

Answer: ()

10. The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6 × 1016 The frequency of revolution of the electron in its first excited state (in s1) is:

(a)  6.2 × 1015

(b)  1.6 × 1014

(c)  7.8× 1014

(d) 5.6 × 1012

Answer: (c)

11. A LCR circuit behaves like a damped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant ‘b’, the correct equivalence will be

(a) 

(b)  L ↔ k, C ↔ b, R ↔ m

(c)  L ↔ m, C ↔ k, R ↔ b

(d) 

Answer: (d)

12. Visible light of wavelength 6000 × 108 cm falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minima is at 60° from the central maxima. If the first minimum is produced at θ1, then θ1 is close to

(a)  20°

(b)  30°

(c)  45°

(d) 25°

Answer: (d)

13. The radius of gyration of a uniform rod of length l about an axis passing through a point l/4 away from the center of the rod, and perpendicular to it, is

(a) 

(b)

(c)  

(d)

Answer: (a)

14. A satellite of mass m is launched vertically upward with an initial speed u from the surface of the earth. After it reaches height R(R = radius of earth), it ejects a rocket of mass m/10 so that subsequently the satellite moves in a circular orbit, The kinetic energy of the rocket is (G = gravitational constant; M is the mass of earth)

(a) 

(b) 

(c) 

(d) 

Answer: (a)

15. Three point particles of mass 1 kg, 1.5 kg and 2.5 kg are placed at three corners of a right triangle of sides 4.0 cm, 3.0 cm and 5.0 cm as shown in the figure. The centre of mass of the system is at the point:

(a)  0.9 cm right and 2.0 cm above 1 kg mass

(b)  2.0 cm right and 0.9 cm above 1 kg mass

(c)  1.5 cm right and 1.2 cm above 1 kg mass

(d) 0.6 cm right and 2.0 cm above 1 kg mass

Answer: (a)

16. If we need a magnification of 375 of from a compound microscope of tube length 150 mm and an objective of focal length 5 mm, the focal length of the eye-piece should be close to:

(a)  22 mm

(b)  2 mm

(c)  12 mm

(d) 33 mm

Answer: (a)

17. Speed of transverse wave of a straight wire (mass 6.0 g, length 60 cm and area of cross-section 1.0 mm2) is 90 m/s. If the Young’s modulus of wire is 16 × 1011 Nm2, the extension of wire over its natural length is

(a)  0.03 mm

(b)  0.02 mm

(c)  0.04 mm

(d) 0.01 mm

Answer: (a)

18. 1 liter of dry air at STP expands adiabatically to a volume of 3 litres. If γ = 1.4, the work done by air is (34 = 4.655) (take air to be an ideal gas)

(a)  48 J

(b)  90.5 J

(c)  100.8 J

(d) 60.7 J

Answer: (b)

19. A bob of mass m is tied by a massless string whose other end portion is wound on a fly wheel (disc) of radius r and mass m. When released from the rest, the bob starts falling vertically. When it has covered a distance h, the angular speed of the wheel will be:

(a) 

(b) 

(c) 

(d) 

Answer: (b)

20. A parallel plate capacitor has plates of area A separated by distance ‘d’ between them It is filled with a dielectric which has a dielectric constant varies as k(x) = k(1 + ax), where ‘x’ is the distance measured from one of the plates. If (αd << 1), the total capacitance of the system is best given by t he expression:

(a) 

(b) 

(c) 

(d) 

Answer: (b)

21. A non-isotropic solid metal cube has coefficient of linear expansion as 5 × 105/°C along the x-axis and 5 × 106/°C along y-axis and z-axis. If the coefficient of volumetric expansion of the solid is C × 106/°C then the value of C is___

Answer: (60)

22. A loop ABCDEFA of straight edges has six corner points A(0, 0, 0), B(5, 0, 0), C(5, 5, 0), D(0, 5, 0), E(0, 5, 5), F(0, 0, 5). The magnetic field in this region is  The quantity of flux through the loop ABCDEFA (in Wb) is______

Answer: (175)

23. A carnot engine operates between two reservoirs of temperature 900 K and 300 K. The engine performs 1200 J of work per cycle. The heat energy in (J) delivered by the engine to the low temperature reservoir, in a cycle, is _______

Answer: (600 J)

24. A particle of mass 1 kg slides down a frictionless track (AOC) starting from rest at a point A(height 2 m). After reaching C, the particle continues to move freely in air as a projectile. When it reaches its highest point P(height 1 m) the kinetic energy of the particle (in J) is: (Figure drawn is schematic and not to scale; take g = 10 m/s2)______

Answer: (10)

25. A beam of electromagnetic radiation of intensity 6.4 × 105 W/cm2 is comprised of wavelength. λ = 310 nm. It falls normally on a metal (work function ϕ = 2 eV) of surface area 1 cm2. If one is 103 photons ejects an electron, total number of electrons ejected in 1s is 10x(hc = 1240 eV – nm, 1 eV = 1.6 × 109 J), then x is _________

Answer: (11)

Chemistry

1. The relative strength of interionic/intermolecular forces forces in decreasing order is:

(a)  ion-dipole > dipole-dipole > ion-ion

(b)  dipole-dipole > ion-dipole > ion-ion

(c)  ion-ion > ion-dipole > dipole-dipole

(d) ion-dipole > ion-ion > dipole-dipole

Answer: (c)

2. Oxidation number of potassium in K2O, K2O2 and KO­2, respectively, is:

(a)  +2, +1 and +1/2

(b)  +1, +2 and +4

(c)  +1, +1 and +1

(d) +1, +4, and +2

Answer: (c)

3. At 35°C, the vapour pressure of CS2 is 512 mm Hg and that of acetone is 344 mm Hg. A solution of CS2 in acetone has a total vapour pressure of 600 mm Hg. The false statement amongst the following is:

(a)  CS2 and acetone are less attracted to each other than to themselves

(b)  heat must be absorbed in order to produce the solution at 35°C

(c)  Raoult’s law is not obeyed by this system

(d) a mixture of 100 mL CS2 and 100 mL acetone has a volume < 200 mL

Answer: (d)

4. The atomic radius of Ag is closest to:

(a)  Ni

(b)  Cu

(c)  Au

(d) Hg

Answer: (c)

5. The dipole moments of CCl4, CHCl3 and CH4 are in the order:

(a)  CH4 < CCl4 < CHCl3

(b)  CHCl3 < CH4 = CCl4

(c)  CH4 = CCl4 < CHCl3

(d) CCl4 < CH4 < CHCl3

Answer: (c)

6. The comparison to the zeolite process for the removal of permanent hardness, the synthetic resins method is:

(a)  less efficient as it exchanges only anions

(b)  more efficient as it can exchanges only cations

(c)  less efficient as the resins cannot be regenerated

(d) more efficient as it can exchange both cations as well as anions

Answer: (d)

7. Amongst the following statements, that which was not proposed by Dalton was:

(a)  matter consists of indivisible atoms

(b)  when gases combine or reproduced in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same T & P.

(c)  Chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.

(d) all the atoms of given element have identical properties including identical mass. Atoms of different elements differ in mass.

Answer: (b)

8. The increasing order of pKb for the following compounds will be:

(a)  ii < iii < i

(b)  iii < i < ii

(c)  i < ii < iii

(d) ii < i < iii

Answer: (d)

9. What is the product of the following reaction?

Answer: (b)

10. The number of orbitals associated with quantum number n = 5, ms = +1/2 is:

(a)  11

(b)  15

(c)  25

(d) 50

Answer: (c)

11. The purest form of commercial iron is:

(a)  cast iron

(b)  wrought iron

(c)  scrap iron and pig iron

(d) pig iron

Answer: (b)

12. The theory that can completely/properly explain the nature of bonding is [Ni(CO)4] is:

(a)  Werner’s theory

(b)  Crystal Field Theory

(c)  Molecular Orbital Theory

(d) Valence Bond Theory

Answer: (c)

13. The IUPAC name of the complex [Pt(NH­3)2Cl(NH2CH3)]Cl is:

(a)  Diamminechlorido(methanamine) platinum(II) chloride

(b)  Bisammine (methanamine) chloridoplatinum (II) chloride

(c)  Diammine (methanamine) chloridoplatinum (II) chloride

(d) Diamminechlorido (amino methane) platinum (II) chloride

Answer: (a)

14. 1-methyl ethylene oxide when treated with an excess of HBr produces:

Answer: (c)

15. Consider the following reaction:

The product ‘X’ is used:

(a)  in protein estimation as an alternative to ninhydrin

(b)  as food grade colourant

(c)  in laboratory test for phenols

(d) in acid-base titration as an indicator

Answer: (d)

16. Match the following:

Answer: (b)

17. Given that the standard potential; (E°) of Cu2+/Cu and Cu+/Cu are 0.34 V and 0.522 V respectively, the E° of Cu2+/Cu+ is:

(a)  +0.158 V

(b)  −0.158 V

(c)  0.182 V

(d) −0.182 V

Answer: (a)

18. A solution of m-chloroaniline, m-chlorophenol and m-chlorobenzoic acid in ethyl acetate was extracted initially with a saturated solution of NaHCO3 to give fraction A. The left over organic phase was extracted with dil. NaOH solution to give fraction B. The final organic layer was labeled as fraction C. Fraction A, B and C, contain respectively.

(a)  m-chlorobenzoic acid, m-chlorophenol and m-chloroaniline

(b)  m-cholrophenol, m-chlorobenzoic acid and m-chloroaniline

(c)  m-chloroaniline, m-chlorobenzoic acid and m-chlorophenol

(d) m-chlorobenzoic acid, m-chloroaniline and m-chlorophenol

Answer: (a)

19. The electron gain enthalpy (in kJ/mol) of fluorine, chlorine, bromine, and iodine, respectively, are:

(a)  −333, −325, −349 and −296

(b)  −333, −349, −325 and −296

(c)  −296, −325, −333 and −349

(d) −349, −333, −325 and −296

Answer: (b)

20. Consider the following reactions:

Which of these reaction(s) will not produce Saytezff product?

(a)  b and d

(b)  d only

(c)  a, c and d

(d) c only

Answer: (d)

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21. Two solutions A and B each of 100 L was made by dissolving 4 g of NaOH and 9.8 g of H2SO4 in water, respectively. The pH of the resulting solution obtained from mixing 40 L of Solution A and 10 L of Solution B is :

Answer: (10.6)

22. During the nuclear explosion, one of the products is 90Sr with half of 6.93 years. If 1 μg of 90Sr was absorbed in the bones of a newly born baby in place of Ca, how much time, in years, is required to reduce it by 90% if it is not lost metabolically

Answer: (23.03)

23. Chlorine reacts with hot and concentrated NaOH and produces compounds (X) and (Y). Compound (X) gives white precipitate with silver nitrate solution. The average bond order between Cl and O atoms in (Y) is

Answer: (1.67)

24. The number of chiral carbons in chloramphenicol is:

Answer: (2)

25. For the reaction A(l) → 2B(g)

∆U = 2.1 kcal, ∆S = 20 calK1 at 300 K, Hence ∆G in kcal is

Answer: (2.7)

Mathematics

1. The area of the region, enclosed by the circle x2 + y2 = 2, which is not common to the region bounded by the parabola y2 = x and the straight line y = x, is

(a)  1/3(12π – 1)

(b)  1/6(12π – 1)

(c)  1/3(6π – 1)

(d) 1/6(24π – 1)

Answer: (b)

2. Total number of six-digit numbers in which only and all five digits 1, 3, 5, 7 and 9 appear, is

(a)  56

(b)  1/2(6!)

(c)  6!

(d) 5/2(6!)

Answer: (d)

3. An unbiased coin is tossed 5 times. Suppose that a variable X is assigned the value k when k consecutive heads are obtained for k = 3, 4, 5, otherwise X takes the value − The expected value of X, is

(a)  1/8

(b)  3/16

(c)  −1/8

(d) −3/16

Answer: (a)

4. If  where z = x +  iy, then the point (x, y) lies on a

(a)  circle whose centre is at (−1/2, −3/2).

(b)  straight line whose slope is 3/2.

(c)  circle whose diameter is √5/2.

(d) straight line whose slope is −2/3.

Answer: (c)

5. If f(a + b + 1 – x) = f(x) ∀ x, where a and b are fixed positive real numbers, then  is equal to

(a) 

(b) 

(c) 

(d) 

Answer: (c)

6. If the distance between the foci of an ellipse is 6 and the distance between its directrices is 12, then the length of its latus rectum is

(a)  2√3

(b)  √3

(c)  3/√2

(d) 3√2

Answer: (d)

7. The logical statement (p ⇒ q) ⋀ (q ⇒ ~ p) is equivalent to

(a)  ~ p

(b)  p

(c)  q

(d) ~ q

Answer: (a)

8. The greatest positive integer k, for which 49k + 1 is a factor of the sum 49125 + 49124 + … + 492 + 49 + 1, is

(a)  32

(b)  60

(c)  65

(d) 63

Answer: (d)

9. A vector  lies in the plane of the vectors,  If  bisects the angle between  then

(a) 

(b) 

(c) 

(d) 

Answer: (*)

10. If  where  is

(a)  −1/4

(b)  4/3

(c)  4

(d) −4

Answer: (c)

11. If y = mx + 4 is a tangent to both the parabolas, y 2 = 4x and x2 = 2by, then b is equal to

(a)  −64

(b)  128

(c)  −128

(d) −32

Answer: (c)

12. Let α be a root of the equation x2 + x + 1 = 0 and the matrix  then the matrix A31 is equal to

(a)  A

(b)  A2

(c)  A3

(d) I3

Answer: (c)

13. If g(x) = x2 + x – 1 and (gof)(x) = 4x2 – 10x + 5, then f(5/4) is equal to

(a)  −3/2

(b)  −1/2

(c)  1/2

(d) 3/2

Answer: (b)

14. Let α and β are two real roots of the equation (k + 1) tan2x – √2λ tan x = 1 – k, where (k ≠ −1) and λ are real numbers. If tan2(α + β) = 50, then value of λ is

(a)  5√2

(b)  10√2

(c)  10

(d) 5

Answer: (c)

15. Let P be a plane passing through the points (2, 1, 0), (4, 1, 1) and (5, 0, 1) and R be any point (2, 1, 6).

(a)  (6, 5, 2)

(b)  (6, 5, −2)

(c)  (4, 3, 2)

(d) (3, 4, −2)

Answer: (b)

16. Let xk + yk = ak, (a, k > 0) and  then k is

(a)  1/3

(b)  3/2

(c)  2/3

(d) 4/3

Answer: (c)

17. Let the function f:[−7, 0] → R be continuous on [−7, 0] and differentiable on (−7, 0). If f(−7) = −3 and f’(x) ≤ 2, for all x ∈ (−7, 0), then for all such functions f, f(−1) + f(0) lies in the interval:

(a)  [−6, 20]

(b)  (−∞, 20]

(c)  (−∞, 11]

(d) [−3, 11]

Answer: (b)

18. If y = y(x) is the solution of the differential equation,  such that y(0) = 0, then y(1) is equal to

(a)  loge 2

(b)  2e

(c)  2 + loge 2

(d) 1 + loge 2

Answer: (d)

19. Five numbers are in A.P., whose sum is 25 and product is 2520. If one of these five numbers is −1/2, then the greatest number amongst them is

(a)  16

(b)  27

(c)  7

(d) 21/2

Answer: (a)

20. If the system all linear equations

2x + 2ay + az = 0

2x + 3by + bz = 0

2x + 4cy + cz = 0,

where a, b, c ∈ R are non-zero and distinct; has non-zero solution, then

(a)  a + b + c = 0

(b)  a, b, c are in A.P.

(c)  1/a, 1/b, 1/c are in A.P.

(d) a, b, c are in G.P.

Answer: (c)

21. 

Answer: (36)

22. If variance of first n natural numbers is 10 and variance of first m even natural numbers is 16, m + n is equal to _______.

Answer: (18)

23. If the sum of the coefficients of all even powers of x in the product (1 + x + x2 + x3 … . + x2n) (1 – x + x2 – x3 … . + x2n) is 61, then n is equal to_____

Answer: (30)

24. Let S be the set of points where the function, f(x) = |2 − |x – 3||, x ∈ R, is not differentiable. Then, the value of  is equal to __________.

Answer: (3)

25. Let A(1, 0), B(6, 2), C(3/2, 6) be the vertices of a triangle ABC. If P is a point inside the triangle ABC such that the triangles APC, APB and BPC have equal areas, then the length of the line the segment PQ, where Q is the point  is ________

Answer: (5)

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