MODEL SOLVED PAPER FOR UGC NET COMPUTER SCIENCE JUNE 2014

MODEL SOLVED PAPER FOR UGC NET JUNE 2014

1. A chip having 200 gates will be classified as

(A) SSI
(B) MSI
(C) LSI
(D) VLSI

Ans:-B

Note:
Small Scale Integration(SSI) - <10
Medium Scale Integration(MSI) - between 10 to 1000
Large Scale Integration(LSI) – Greater than 1000
Very Large Scale Integration(VLSI) – greater than 100000.

2. Consider the following statements :
I. Recursive languages are closed under complementation.
II. Recursively enumerable languages are closed under union.
III. Recursively enumerable languages are closed under complementation.
Which of the above statements are true ?

(A) I only
(B) I and II
(C) I and III
(D) II and III

Ans:-B

Very often asked question in UGC.

Explanation:-
Recursive languages are closed under the following operations.

1.                  Concatenation

2.                  Kleene Star

3.                  Union

4.                  Intersection

5.                  Complement

6.                  Set difference

Recursively enumerable languages are closed under the following operations.

1.                  Kleene star

2.                  Concatenation

3.                  Union

4.                  Intersection

3. Consider the following page trace : 4,3, 2, 1, 4, 3, 5, 4, 3, 2, 1, 5 Percentage of page fault that would occur if FIFO page replacement algorithm is used with number of frames for the JOB m = 4 will be
(A) 8
(B) 9
(C) 10
(D) 12 

Ans:-C

Opearating system based question.

Explanation:-
The reference string is 4,3,2,1,4,3,5,4,3,2,1,5
The number of frames m = 4
The first 4 references 4,3,2,1 cause page faults and brought into the empty frames.

So there will be 4 page faults initially.
The next reference 4 is already available in the frame  and so there will be no page fault.
Similarly, The next reference 3 is also already available and so there is no page fault.
The next reference (5) replaces page 4 which was brought in to first frame. 

So, No of page faults=5. Because we already had 4 page faults.
Next reference (4) replaces page 3 which is the next to come in.

No of page faults=6.

Next reference (3) replaces 2.No of page faults till now=7.
Next reference (2) replaces 1 which was the last of the pages to come in.

No of page faults till now=8.
Next reference (1) replaces 5 which was the first to come in in the second cycle. No of page faults will increase to 9.
The last reference in the reference string is 5 which will replace 4. No of page faults will be finally 10.

So the answer is 10.

4. Evaluate the following postfix expression 579*+493/+–

Ans.:61.

Explanation:

1. 7*9=63

63+5=68     Part  1

2. 9/3=3

3+4=7     Part   2

Part 1 – Part 2

Result: 68-7=61

5. Which of the following strings is in the language defined by grammar
S → 0A,

A → 1A/0A/1
(A) 01100
(B) 00101
(C ) 10011
(D) 11111 

Ans:-B

Hint: Any production needs to be started from S, which is the starting point.

From the above given symbols, we can substitute A with 1A or 0A or 1 as per the requirements of the result.

Explanation:- Non terminals in the above grammar are S and A.

 Non terminals are generally denoted by capital letters.

Terminals in the given problem are 0 and 1.

The start symbol of the grammar is S, which is the starting point of the production. S->0A. So rule out strings beginning with 1. so that leaves us with two options A and B.

Start of production:

S->0A
->00A                  Hint: In place of A, we are substituting 0A
->001A                Hint: In place of A, we are substituting 1A

->0010A               Hint: In place of A, we are substituting 0A

->00101               Hint: In place of A, we are substituting 1

So the option B is correct.

6. Interner layer provides

Quality of service

Routing

Addressing.

7. The search algorithm that helps to find optimal solution.

Breadth First search.

 8. The program used to determine the round-trip delay between a workstation and a destination address is

Trace route

9. Some of the data link layer standards are.

Ethernet

Frame relay

10 base-T

Token ring.

10. The topology with highest reliasbility is

Mesh topology.

11. What is the maximum number of nodes in a B-tree of order 10 of depth 3 (root at depth 0) ?
 (A) 111
(B) 999
(C) 9999
(D) None of the above

Ans:-C

Explanation:- 

Formula for Calculating maximum number of nodes in a B-tree
=>m^h+1-1

Where m is the order

h is the depth
Here, m=10 and h=3. So the formula becomes
10⁴-1 which is 10000-1=9999 and therefore C is the correct option  (Hint:10^4=10*10*10*10=10000)

12. What is used to regulate the flow of electrons in CRT.

Control grid.

13. The thin or nonexistent layer in broadcast network is

Network layer

14. The most powerful parsing method is

Canonical LR

15. Shift reduce parsers are also called as

Bottom up parsers.

 All the Best for UGC NET exam.

With Regards,

Tanvir Khan