## UGC NET CS 2009 Dec-Paper-2

 Question 1
If she is my friend and you are her friend, then we are friends. Given this, the friend relationship in this context is ____________. (i) commutative (ii) transitive (iii) implicative (iv) equivalence
 A (i) and (ii) B (iii) C (i), (ii), (iii) and (iv) D None of these
Question 1 Explanation:
→ Initially calculate the possible cases of a relation i.e., R={(A,B), (C,B), (A,C)}
→ Now check whether the relation is transitive or commutative or etc..,
If a relation is commutative then if (A,B) present in the relation then (B,A) also need to exists. but in the relation (B,A) is not present. so given relation is not commutative.
 Question 2
Circle has ____________
 A No vertices B Only 1 vertex C ∞ vertices D None of these
Question 2 Explanation:
In graph theory, a circle graph is the intersection graph of a set of chords of a circle.
→ A circle graph is an undirected graph whose vertices can be associated with chords of a circle such that two vertices are adjacent if and only if the corresponding chords cross each other.
→ Circle does not have vertices.

 Question 3
If in an error detection and correction code a message M : “You are good students” is stored as M' : Youare areyou aregood goodare goodstudents studentsgood. What is the space required to store M' in general ? (assume that ‘n’ is the length of M)
 A 2n B 3n C 4n D less than 4n
Question 3 Explanation:
Message M: “You are good students” is stored as M'
The message length is "n".
The following string is "Youare areyou aregood goodare goodstudents studentsgood" divided as follows
You are good students --- n
are you students good ---- n
are good ----- n
good are ----- n
Then total messages length is 4n.
 Question 4
P: “Program is a step by step execution of the instructions”. Given P, which of the following is true ?
 A Program is a subset of an instruction set. B Program is a sequence of a subset of an instruction set. C Program is a partially ordered set of an instruction set. D All of the above
Question 4 Explanation:
→ Set A is a subset of another set B if all elements of the set A are elements of the set B Program is a collection of statements and that collection may be subset so the option(a) is true.
→ In the program, the execution of instructions will be performed sequentially.So option (b) also true.
→ A partially ordered set (also poset) formalizes and generalizes the intuitive concept of an ordering, sequencing, or arrangement of the elements of a set. According to the above definition, the option (c) also true.
 Question 5
In a MIU puzzle, either of the letters M, I or U could go as a start symbol. Production rules are given below :
R1 : U → IU
R2 : M.x → M.x.x where . .. is string concatenation operator. Given this, which of the following holds for
(i) MIUIUIUIUIU
(ii) MIUIUIUIUIUIUIUIU
 A Either (i) or (ii) but not both of these are valid words. B Both (i) and (ii) are valid words and they take identical number of transformations for the production. C Both (i) and (ii) are valid words but they involve different number of transformations in the production. D None of these
Question 5 Explanation:
(i) string-> MIUIUIUIUIU
It has M (5 times ) IU
Production 2 says: M.x-> M.x.x
So
MU-> MUU again using it
MUU-> MUUU -> MUUUU ->MUUUUU
Now using prod 1: Last U-> IU
MUUUUU -> MIUUUUU
MIUUUUU -> MIUIUUUU
MIUIUUU ----------------> MIUIUIUIUIU
 Question 6
The simplified form of the Boolean expression (X + Y + XY) (X + Z) is
 A X + Y + ZX + Y B XY – YZ C X + YZ D XZ + Y
Question 6 Explanation:
Given boolean expression is (X+Y+XY) (X+Z)
Step-1: (X (1+Y)+Y) (X+Z) /* To take common as X */
Step-2: (X+Y) (X+Z) /* To take common as X */
Step-3: (X+YZ)
 Question 7
Identify the logic function performed by the circuit shown

 A exclusive OR B exclusive NOR C NAND D NOR
Question 7 Explanation:
We can solve this problem by two methods
1. Using Boolean expression
2. Using truth table

 Question 8
The highest noise margin is offered by
 A BICMOS B TTL C ECL D CMOS
Question 8 Explanation:
Emitter Coupled Logic (ECL)
The storage time is eliminated as the transistors are used in difference amplifier mode and are never driven into saturation.
1. Fastest among all logic families
2. Lowest propagation delay.
Complementary metal oxide semiconductor(CMOS)
The power dissipation is usually 10nW per gate depending upon the power supply voltage, output load etc.
1. Lowest power dissipation
2. Excellent noise immunity
3. High packing density
4. Wide range of supply voltage
5. Highest fan out among all logic families
 Question 9
The answer of the operation (10111)2* (1110)2 in hex equivalence is
 A 150 B 241 C 142 D 101011110
Question 9 Explanation:

 Question 10
How many 1’s are present in the binary representation of 3 × 512 + 7 × 64 + 5 × 8 + 3
 A 8 B 9 C 10 D 11
Question 10 Explanation:
Given expression is 3 × 512 + 7 × 64 + 5 × 8 + 3
We can write above statement based on precedence is (3 * 512) + (7 * 64) + (5 * 8) + 3
Step-1: 1536+448+40+3
Step-2: (2027)10
Step-3: Equivalent binary number is (‭011111101011‬)2
Note: Total number of 1’s is 9.
 Question 11
Recursive functions are executed in a
 A First in first out-order B Last in first out-order C Parallel fashion D Load balancing
Question 11 Explanation:
Recursive functions are executed in a last in first out-order. It is using stack data structure to evaluate recursive functions.
 Question 12
What would be the output of the following program, if run from the command line as “myprog 123”?
main(int argc,char∗argv[ ])
{
int i;
i=argv[1] + argv[2] + argv[3];
printf (“%d”, i);
}
 A 123 B 6 C Error D “123”
Question 12 Explanation:
The input given in string type. But we need to print the value in integer type. For this we have to use type casting (or) atoi function. So, it will give output is “error”
Note: argv[1], argv[2] and argv[3] is string type.
There are 12 questions to complete.

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