## UGC NET Computer Science Solved Paper -III Dec 2014

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.

(C) 75 n.sec. (D) 82.5 n.sec.

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

(C) Software interrupts (D) None of the above

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

(C) 166 chars/second and 0.8 seconds

(D) 250 chars/second and 0.4 seconds

NOTE: All the above options are wrong. The correct answer should be 125 chars/second and 1.6 seconds

4. Match the following 8085 instructions with the flags :

List – I List – II

a. XCHG i. only carry flag is affected.

b. SUB ii. no flags are affected.

c. STC iii. all flags other than carry flag are affected.

d. DCR iv. all flags are affected.

Codes :

a b c d

(A) iv i iii ii

(B) iii ii i iv

(C) ii iii i iv

(D) ii iv i iii

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

LXI B, 0007 H

LOP : DCX B

MOV A, B

ORA C

JNZ LOP

(A) 05 (B) 07

(C) 09 (D) 00

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

(C) 01, 1, 0, 0 (D) 00, 0, 1, 1

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

(C) II and III only (D) II only

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

(C) I and IV (D) II and III

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

(C) Log buffer (D) Thomas

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

(C) Φ, φ (D) ABC, E

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

(C) Both are correct (D) None of the statements are correct.

12. Which of the following is false ?

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

(B) Every BCNF relation is in 3NF.

(C) 1 NF, 2 NF, 3 NF and BCNF are based on functional dependencies.

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

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

(A) Graphical languages (B) General-purpose languages

(C) Linear-list notations (D) None of the above

14. Match the following :

List – I List – II

a. Tablet, Joystick i. Continuous devices

b. Light Pen, Touch Screen ii. Direct devices

c. Locator, Keyboard iii. Logical devices

d. Data Globe, Sonic Pen iv. 3D interaction devices

Codes :

a b c d

(A) ii i iv iii

(B) i iv iii ii

(C) i ii iii iv

(D) iv iii ii i

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

(A) Halftoning (B) Dithering

(C) Error diffusion (D) None of the above

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 _______

(A) A’ ( –1,√2 –1), B'( –1, 2√2 –1), C’ (3/2 √2 –1, 9/2 √2 –1)

(B) A’ (√2 –1,-1), B'( 2√2 –1, –1) , C’ (3/2 √2 –1, 9/2 √2 –1)

(C) A’ ( –1,√2 –1), B'( 2√2 –1,–1), C’ (3/2 √2 –1, 9/2 √2 –1)

(D) A’ ( –1,√2 –1), B'( 2√2 –1,–1), C’ (9/2 √2 –1, 3/2 √2 –1)

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, ni is inner normal)

(A) (P1 – fi) .ni / (P2 – P1) . ni (B) (fi – P1) . ni / (P2 – P1) . ni

(C) (P2 – fi) . ni / (P1 – P2) . ni (D) (fi – P2) . ni / (P1 – P2) . ni

18. Match the following :

a. Cavalier Projection i. The direction of projection is chosen so that there is no foreshortening of

lines perpendicular to the xy plane.

b. Cabinet Projection ii. The direction of projection is chosen so that lines perpendicular to the xy

planes are foreshortened by half their lengths.

c. Isometric Projection iii. The direction of projection makes equal angles with all of the principal

axis.

d. Orthographic Projection iv. Projections are characterized by the fact that the direction of projection

is perpendicular to the view plane.

Codes :

a b c d

(A) i iii iv ii

(B) ii iii i iv

(C) iv ii iii i

(D) i ii iii iv

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.

(C) S2 and S1 are true. (D) S1, S2, S3 are true.

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

x = x * (a + b) – 5;

(A) 12 (B) 11

(C) 10 (D) 07

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.

(C) MPI_Send and MPI_Recv are non-blocking message passing routines of MPI.

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

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

δ(q0, a, 0) = {(q1, 10)}

δ(q1, a, 1) = {(q1, 11)}

δ(q1, b, 1) = {(q2, λ)}

δ(q2, b, 1) = {(q2, λ)}

δ(q2, λ, 0) = {(q0, λ)}

Accepts the language

(A) L = {a^{ n} b^{ m) }| n, m ≥ 0} (B) L = {a^{ n} b^{n) }| n ≥ 0}

(C) L = {a^{ n} b^{ m) }| n, m > 0} (D) L = {a^{ n} b^{n) }| n > 0}

23. Given two languages :

L1 = {(ab)^{ n} a^{ k} | n > k, k ≥ 0}

L2 = {a^{ n} 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.

(C) L1 is regular and L2 is regular.

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

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

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

(B) a* bbbbb*

(C) (λ + a + aa + aaa)b* + (a + b)* ba(a + b)*

(D) None of the above

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)

(C) n(n + 1)/2 (D) n(n – 1)/2

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

(C) 360 (D) 400

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

(A) Sequence number (B) Fragment offset

(C) Checksum (D) Window size

28. What is the propagation time if the distance between the two points is 48,000 ? Assume the propagation speed to be 2.4 × 10^{8 }metre/second in cable.

(A) 0.5 ms (B) 20 ms

(C) 50 ms (D) 200 ms

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

(A) Stop-and-wait (B) HDLC

(C) Sliding window (D) Go-back-N

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.

(C) Both private key and public key are kept by the receiver.

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

31. Any decision tree that sorts n elements has height

(A) Ω(n) (B) Ω(*lg*n)

(C) Ω(n*lg*n) (D) Ω(n^{2})

32. Match the following :

List – I List – II

a. Bucket sort i. O(n^{3}*lg*n)

b. Matrix chain multiplication ii. O(n^{3})

c. Huffman codes iii. O(n*lg*n)

d. All pairs shortest paths iv. O(n)

Codes :

a b c d

(A) iv ii i iii

(B) ii iv i iii

(C) iv ii iii i

(D) iii ii iv i

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

(C) CLIQUE ≤ P SUBSET_SUM

(D) None of the above

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

(C) Greedy algorithm, Dynamic programming algorithm

(D) Dynamic programming algorithm, Greedy algorithm

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

(C) 20 (D) 100

*1*

*2*