COMPUTER SCIENCE

PAPER – III

Note : This paper contains seventy five (75) objective type questions of two (2) marks each. All questions are compulsory.

1. A hierarchical memory system that uses cache memory has cache access time of 50 nano seconds, main memory access time of 300 nano seconds, 75% of memory requests are for read, hit ratio of 0.8 for read access and the write-through scheme is used. What will be the average access time of the system both for read and write requests ?

(A) 157.5 n.sec.

(B) 110 n.sec.

(D) 82.5 n.sec.

Ans: (A)

2. For switching from a CPU user mode to the supervisor mode following type of interrupt is most appropriate

(A) Internal interrupts

(B) External interrupts

(D) None of the above

Ans: (C)

3. In a dot matrix printer the time to print a character is 6 m.sec., time to space in between characters is 2 m.sec., and the number of characters in a line are 200. The printing speed of the dot matrix printer in characters per second and the time to print a character line are given by which of the following options ?

(A) 125 chars/second and 0.8 seconds

(B) 250 chars/second and 0.6 seconds

(D) 250 chars/second and 0.4 seconds

Ans: (A)

4. Match the following 8085 instructions with the flags :

Ans: (D)

5. How many times will the following loop be executed ?

(A) 05

(B) 07

(D) 00

Ans: (B)

6. Specify the contents of the accumulator and the status of the S, Z and CY flags when 8085 microprocessor performs addition of 87 H and 79 H.

(A) 11, 1, 1, 1

(B) 10, 0, 1, 0

(D) 00, 0, 1, 1

Ans: (D)

7. Location transparency allows :

I. Users to treat the data as if it is done at one location.

II. Programmers to treat the data as if it is at one location.

III. Managers to treat the data as if it is at one location.

Which one of the following is correct ?

(A) I, II and III

(B) I and II only

(D) II only

Ans: (A)

8. Which of the following is correct ?

I. Two phase locking is an optimistic protocol.

II. Two phase locking is pessimistic protocol

III. Time stamping is an optimistic protocol.

IV. Time stamping is pessimistic protocol.

(A) I and III

(B) II and IV

(D) II and III

Ans: (D)

9. __________ rules used to limit the volume of log information that has to be handled and processed in the event of system failure involving the loss of volatile information.

(A) Write-ahead log

(B) Check-pointing

(D) Thomas

Ans: (B)

10. Let R = ABCDE is a relational scheme with functional dependency set F = {A → B, B → C, AC → D}. The attribute closures of A and E are

(A) ABCD, Φ

(B) ABCD, E

(D) ABC, E

Ans: (B)

11. Consider the following statements :

I. Re-construction operation used in mixed fragmentation satisfies commutative rule.

II. Re-construction operation used in vertical fragmentation satisfies commutative rule

Which of the following is correct ?

(A) I

(B) II

(D) None of the statements are correct.

Ans: (D)

12. Which of the following is false ?

(A) Every binary relation is never be in BCNF.

(B) Every BCNF relation is in 3NF.

(D) Multivalued Dependency (MVD) is a special case of Join Dependency (JD).

Ans: (A)

13. Which of the following categories of languages do not refer to animation languages ?

(A) Graphical languages

(B) General-purpose languages

(D) None of the above

Ans: (D)

14. Match the following :

Ans: (C)

15. A technique used to approximate halftones without reducing spatial resolution is known as _________.

(A) Halftoning

(B) Dithering

(D) None of the above

Ans: (B)

16. Consider a triangle represented by A(0, 0), B(1, 1), C(5, 2). The triangle is rotated by 45 degrees about a point P(–1, –1). The co-ordinates of the new triangle obtained after rotation shall be _______

Ans: (A)

17. In Cyrus-Beck algorithm for line clipping the value of t parameter is computed by the relation :

(Here P₁ and P₂ are the two end points of the line, f is a point on the boundary, n₁ is inner normal)

Ans: (B)

18. Match the following :

Ans: (D)

19. Consider the following statements S1, S2 and S3 :

S1 : In call-by-value, anything that is passed into a function call is unchanged in the caller’s scope when the function returns.

S2 : In call-by-reference, a function receives implicit reference to a variable used as argument.

S3 : In call-by-reference, caller is unable to see the modified variable used as argument.

(A) S3 and S2 are true.

(B) S3 and S1 are true.

(D) S1, S2, S3 are true.

Ans: (C)

20. How many tokens will be generated by the scanner for the following statement ?

x = x * (a + b) – 5;

(A) 12

(B) 11

(D) 07

Ans: (A)

21. Which of the following statements is not true ?

(A) MPI_Isend and MPI_Irecv are non-blocking message passing routines of MPI.

(B) MPI_Issend and MPI_Ibsend are non-blocking message passing routines of MPI.

(D) MPI_Ssend and MPI_Bsend are blocking message passing routines of MPI.

Ans: (C)

22. The pushdown automation M = ({q₀, q₁, q₂}, {a, b}, {0, 1}, d, q₀, 0, {q₀}) with

Accepts the language

(A) L = {aⁿ b^m | n, m ³ 0}

(B) L = {an bⁿ | n ³ 0}

(D) L = {an bⁿ | n > 0}

Ans: (B)

23. Given two languages :

L₁ = {(ab)ⁿ ak | n > k, k ≥ 0}

L₂ = {aⁿ b^m | n ≠ m}

Using pumping lemma for regular language, it can be shown that

(A) L₁ is regular and L₂ is not regular.

(B) L₁ is not regular and L₂ is regular.

(D) L₁ is not regular and L₂ is not regular.

Ans: (D)

24. Regular expression for the complement of language L = {aⁿ b^m | n ≥ 4, m ≤ 3} is

(A) (a + b)* ba(a + b)*

(B) a* bbbbb*

(D) None of the above

Ans: (D)

25. For n devices in a network, ________ number of duplex-mode links are required for a mesh topology.

(A) n(n + 1)

(B) n (n – 1)

(D) n(n – 1)/2

Ans: (D)

26. How many characters per second (7 bits + 1 parity) can be transmitted over a 3200 bps line if the transfer is asynchronous ? (Assuming 1 start bit and 1 stop bit)

(A) 300

(B) 320

(D) 400

Ans: (B)

27. Which of the following is not a field in TCP header ?

(A) Sequence number

(B) Fragment offset

(D) Window size

Ans: (B)

28. What is the propagation time if the distance between the two points is 48,000 ? Assume the propagation speed to be 2.4 × 10⁸ metre/second in cable.

(A) 0.5 ms

(B) 20 ms

(D) 200 ms

Ans: (ALL OPTIONS ARE CORRECT)

29. __________ is a bit-oriented protocol for communication over point-to-point and multipoint links.

(A) Stop-and-wait

(B) HDLC

(D) Go-back-N

Ans: (B)

30. Which one of the following is true for asymmetric-key cryptography ?

(A) Private key is kept by the receiver and public key is announced to the public.

(B) Public key is kept by the receiver and private key is announced to the public.

(D) Both private key and public key are announced to the public.

Ans: (A)

31. Any decision tree that sorts n elements has height

(A) Ω(n)

(B) Ω(lgn)

(D) Ω(n²)

Ans: (C)

32. Match the following :

Ans: (C)

33. We can show that the clique problem is NP-hard by proving that

(A) CLIQUE ≤ P 3-CNF_SAT

(B) CLIQUE ≤ P VERTEX_COVER

(D) None of the above

Ans: (D)

34. Dijkstra algorithm, which solves the single-source shortest–paths problem, is a _________, and the Floyd-Warshall algorithm, which finds shortest paths between all pairs of vertices, is a _________

(A) Greedy algorithm, Divide-conquer algorithm

(B) Divide-conquer algorithm, Greedy algorithm

(D) Dynamic programming algorithm, Greedy algorithm

Ans: (C)

35. Consider the problem of a chain <A₁, A₂, A₃> of three matrices. Suppose that the dimensions of the matrices are 10 × 100, 100 × 5 and 5 × 50 respectively. There are two different ways of parenthesization : (i) ((A₁ A₂)A₃) and (ii) (A₁(A2 A₃)). Computing the product according to the first parenthesization is ________ times faster in comparison to the second parenthesization.

(A) 5

(B) 10

(D) 100

Ans: (B)

36. Suppose that we have numbers between 1 and 1000 in a binary search tree and we want to search for the number 365. Which of the following sequences could not be the sequence of nodes examined ?

(A) 4, 254, 403, 400, 332, 346, 399, 365

(B) 926, 222, 913, 246, 900, 260, 364, 365

(D) 4, 401, 389, 221, 268, 384, 383, 280, 365

Ans: (C)

37. Which methods are utilized to control the access to an object in multi-threaded programming ?

(A) Asynchronized methods

(B) Synchronized methods

(D) None of the above

Ans: (B)

38. How to express that some person keeps animals as pets ?

Ans: (A)

39. Converting a primitive type data into its corresponding wrapper class object instance is called

(A) Boxing

(B) Wrapping

(D) Autoboxing

Ans: (D)

40. The behaviour of the document elements in XML can be defined by

(A) Using document object

(B) Registering appropriate event handlers

(D) All of the above

Ans: (D)

41. What is true about UML stereotypes ?

(A) Stereotype is used for extending the UML language.

(B) Stereotyped class must be abstract

(D) UML profiles can be stereotyped for backward compatibility

Ans: (A)

42. Which method is called first by an applet program ?

(A) start( )

(B) run( )

(D) begin( )

Ans: (C)

43. Which one of the following is not a source code metric ?

(A) Halstead metric

(B) Function point metric

(D) Length metric

Ans: (B)

44. To compute function points (FP), the following relationship is used FP = Count – total × (0.65 + 0.01 × ∑(F_i)) where F_i (i = 1 to n) are value adjustment factors (VAF) based on n questions. The value of n is

(A) 12

(B) 14

(D) 18

Ans: (B)

45. Assume that the software team defines a project risk with 80% probability of occurrence of risk in the following manner :

Only 70 percent of the software components scheduled for reuse will be integrated into the application and the remaining functionality will have to be custom developed. If 60 reusable components were planned with average component size as 100 LOC and software engineering cost for each LOC as $ 14, then the risk exposure would be

(A) $ 25,200

(B) $ 20,160

(D) $ 15,120

Ans: (B)

46. Maximum possible value of reliability is

(A) 100

(B) 10

(D) 0

Ans: (C)

47. ‘FAN IN’ of a component A is defined as

(A) Count of the number of components that can call, or pass control, to a component A

(B) Number of components related to component A

(D) None of the above

Ans: (A)

48. Temporal cohesion means

(A) Coincidental cohesion

(B) Cohesion between temporary variables

(D) Cohesion with respect to time

Ans: (D)

49. Various storage devices used by an operating system can be arranged as follows in increasing order of accessing speed :

(A) Magnetic tapes → magnetic disks → optical disks → electronic disks → main memory → cache → registers

(B) Magnetic tapes → magnetic disks → electronic disks → optical disks → main memory → cache → registers

(D) Magnetic tapes → optical disks → magnetic disks → electronic disks → main memory → cache → registers

Ans: (D)

50. How many disk blocks are required to keep list of free disk blocks in a 16 GB hard disk with 1 kB block size using linked list of free disk blocks ? Assume that the disk block number is stored in 32 bits.

(A) 1024 blocks

(B) 16794 blocks

(D) 1048576 blocks

Ans: (ALL OPTIONS ARE CORRECT)

51. Consider an imaginary disk with 40 cylinders. A request come to read a block on cylinder 11. While the seek to cylinder 11 is in progress, new requests come in for cylinders 1, 36, 16, 34, 9 and 12 in that order. The number of arm motions using shortest seek first algorithm is

(A) 111

(B) 112

(D) 61

Ans: (D)

52. An operating system has 13 tape drives. There are three processes P1, P2 & P3. Maximum requirement of P1 is 11 tape drives, P2 is 5 tape drives and P3 is 8 tape drives. Currently, P1 is allocated 6 tape drives, P2 is allocated 3 tape drives and P3 is allocated 2 tape drives. Which of the following sequences represent a safe state ?

(A) P2 P1 P3

(B) P2 P3 P1

(D) P1 P3 P2

Ans: (A)

53. Monitor is an Interprocess Communication (IPC) technique which can be described as

(A) It is higher level synchronization primitive and is a collection of procedures, variables, and data structures grouped together in a special package.

(B) It is a non-negative integer which apart from initialization can be acted upon by wait and signal operations.

(D) It consists of the IPC primitives implemented as system calls to block the process when they are not allowed to enter critical region to save CPU time.

Ans: (A)

54. In a distributed computing environment, distributed shared memory is used which is

(A) Logical combination of virtual memories on the nodes.

(B) Logical combination of physical memories on the nodes.

(D) All of the above

Ans: (B)

55. Equivalent logical expression for the Well Formed Formula (WFF), ~(∀x) F[x]

(A) ∀x (~F[x])

(B) ~(∃x) F[x]

(D) ∀x F[x]

Ans: (C)

56. An A* algorithm is a heuristic search technique which

(A) is like a depth-first search where most promising child is selected for expansion

(B) generates all successor nodes and computes an estimate of distance (cost) from start node to a goal node through each of the successors. It then chooses the successor with shortest cost.

(C) saves all path lengths (costs) from start node to all generated nodes and chooses shortest path for further expansion.

(D) none of the above

Ans: (B)

57. The resolvent of the set of clauses

(A ∨ B, ~A ∨ D, C ∨ ~B) is

(A) A ∨ B

(B) C ∨ D

(D) A ∨ D

Ans: (B)

58. Match the following :

Ans: (B)

59. Match the following components of an expert system :

Ans: (B)

60. A computer based information system is needed :

I. as it is difficult for administrative staff to process data.

II. due to rapid growth of information and communication technology.

III. due to growing size of organizations which need to process large volume of data.

IV. as timely and accurate decisions are to be taken.

Which of the above statement(s) is/are true ?

(A) I and II

(B) III and IV

(D) II and IV

Ans: (B)

61. Given the recursively enumerable language (L_RE), the context sensitive language (L_CS), the recursive language (L_REC), the context free language (LCF) and deterministic context free language (L_DCF). The relationship between these families is given by

Ans: (D)

62. Match the following :

Ans: (B)

63. According to pumping lemma for context free languages :

Let L be an infinite context free language, then there exists some positive integer m such that any w ∈ L with | w | ≥ m can be decomposed as w = u v x y z

(A) with | vxy | ≤ m such that uvⁱ xyⁱ z ∈ L for all i = 0, 1, 2

(B) with | vxy | ≤ m, and | vy | ≥ 1, such that uvⁱ xyⁱ z ∈ L for all i = 0, 1, 2, …….

(D) with | vxy | ≥ m, and | vy | ≥ 1, such that uvⁱ xyⁱ z ∈ L for all i = 0, 1, 2, …….

Ans: (B)

64. Given two spatial masks

The Laplacian of an image at all points (x, y) can be implemented by convolving the image with spatial mask. Which of the following can be used as the spatial mask ?

(A) only S₁

(B) only S₂

(D) None of these

Ans: (B)

65. Given a simple image of size 10 × 10 whose histogram models the symbol probabilities and is given by

The first order estimate of image entropy is maximum when

Ans: (D)

66. A Butterworth lowpass filter of order n, with a cutoff frequency at distance D₀ from the origin, has the transfer function H(u, v) given by

Ans: (A)

67. If an artificial variable is present in the ‘basic variable’ column of optimal simplex table, then the solution is

(A) Optimum

(B) Infeasible

(D) Degenerate

Ans: (B)

68. The occurrence of degeneracy while solving a transportation problem means that

(A) total supply equals total demand

(B) total supply does not equal total demand

(D) none of these

Ans: (C)

69. Five men are available to do five different jobs. From past records, the time (in hours) that each man takes to do each job is known and is given in the following table :

Find out the minimum time required to complete all the jobs.

(A) 5

(B) 11

(D) 15

Ans: (C)

70. Consider the following statements about a perception :

I. Feature detector can be any function of the input parameters.

II. Learning procedure only adjusts the connection weights to the output layer.

Identify the correct statement out of the following :

(A) I is false and II is false.

(B) I is true and II is false.

(D) I is true and II is true.

Ans: (D)

71. A _________ point of a fuzzy set A is a point x ∈ X at which μA(x) = 0.5

(A) core

(B) support

(D) a-cut

Ans: (C)

72. Match the following learning modes w.r.t. characteristics of available information for learning :

Ans: (A)

73. Which of the following versions of Windows O.S. contain built-in partition manager which allows us to shrink and expand pre-defined drives ?

(A) Windows Vista

(B) Windows 2000

(D) Windows 98

Ans: (A)

74. A Trojan horse is

(A) A program that performs a legitimate function that is known to an operating system or its user and also has a hidden component that can be used for nefarious purposes like attacks on message security or impersonation.

(B) A piece of code that can attach itself to other programs in the system and spread to other systems when programs are copied or transferred.

(C) A program that spreads to other computer systems by exploiting security holes like weaknesses in facilities for creation of remote processes

(D) All of the above

Ans: (A)

75. Which of the following computing models is not an example of distributed computing environment ?

(A) Cloud computing

(B) Parallel computing

(D) Peer-to-peer computing

Ans: (B)

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