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)

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