# UGC NET Computer Science Solved Mcqs Paper II December 2004 - Part 1

1.       AVA = A is called:
(A) Identity law             (B) De Morgan’s law
(C) Idempotent law      (D) Complement law
2.       If f(x) =x+1 and g(x)=x+3 then fofofof is:
(A) g       (B) g+1
(C) g4     (D) None of the above
Explanation:
If f(x)=x+1 and g(x)=x+3, then fog(x)=x+4 and gof(x)=x+4
fof(x)=x+2, fofof(x)=x+3 and fofofof(x)=x+4.=x+3+1=g+1
3.       The context-free languages are closed for:
(i) Intersection                          (ii) Union
(iii) Complementation             (iv) Kleene Star
then
(A) (i) and (iv)               (B) (i) and (iii)
(C) (ii) and (iv)              (D) (ii) and (iii)
4.       The following lists are the degrees of all the vertices of a graph:
(i) 1, 2, 3, 4, 5                (ii) 3, 4, 5, 6, 7
(iii) 1, 4, 5, 8, 6              (iv) 3, 4, 5, 6
then, which of the above sequences are graphic?
(A) (i) and (ii)
(B) (iii) and (iv)
(C) (iii) and (ii)
(D) (ii) and (iv)
Explanation:
Rest can't be graphs as the number of vertices with odd degree in a graph should be even.
In list (i), number of vertices with odd degree is 3.
In list (ii), number of vertices with odd degree is 3.
In list (iii), number of vertices with odd degree is 2.
In list (iv), number of vertices with odd degree is 2.
5.       If Im denotes the set of integers modulo m, then the following are fields with respect to the operations of addition modulo m and multiplication modulo m:
(i) Z23      (ii) Z29
(iii) Z31    (iv) Z33
Then
(A) (i) only
(B) (i) and (ii) only
(C) (i), (ii) and (iii) only
(D) (i), (ii), (iii) and (iv)
6.       An example of a binary number which is equal to its 2’s complement is:
(A) 1100                        (B) 1001
(C) 1000                        (D) 1111
7.       When a tri-state logic device is in the third state, then:
(A) it draws low current
(B) it does not draw any current
(C) it draws very high current
(D) it presents a low impedance
8.       An example of a connective which is not associative is:
(A) AND             (B) OR
(C) EX-OR        (D) NAND
9.       Essential hazards may occur in:
(A) Combinational logic circuits
(B) Synchronous sequential logic circuits
(C) Asynchronous sequential logic circuits working in the fundamental mode
(D) Asynchronous sequential logic circuits working in the pulse mode
10.    The characteristic equation of a T flip-flop is:
(A) Qn+1=TQ’n + T’ Qn
(B) Qn+1=T+Qn
(C) Qn+1=TQn
(D) Qn+1= T’Q’n
The symbols used have the usual meaning.

1. The following lists are the degrees of all the vertices of a graph:
(i) 1, 2, 3, 4, 5 (ii) 3, 4, 5, 6, 7
(iii) 1, 4, 5, 8, 6 (iv) 3, 4, 5, 6
then
(A) (i) and (ii)
(B) (iii) and (iv)
(C) (iii) and (ii)
(D) (ii) and (iv)
1. 