UGC NET CS 2005 Dec-Paper-2
Question 1 |
T is a graph with n vertices. T is connected and has exactly n-1 edges, then :
T is a tree | |
T contains no cycles | |
Every pairs of vertices in T is connected by exactly one path | |
All of these |
Question 1 Explanation:
This is little bit tricky question.
Step-1:
n= number of vertices
n-1 = number of edges
Example: n=5 vertices and n-1=4 edges
Step-2: The above graph T won’t have cycle then we are calling as tree. Here, every pairs of vertices in T is connected by exactly one path.
Note: The above properties is nothing but minimum spanning tree properties.
Step-1:
n= number of vertices
n-1 = number of edges
Example: n=5 vertices and n-1=4 edges
Step-2: The above graph T won’t have cycle then we are calling as tree. Here, every pairs of vertices in T is connected by exactly one path.
Note: The above properties is nothing but minimum spanning tree properties.
Question 2 |
If the proposition ¬ P → Q is true, then the truth value of the proportion ¬ PV (P → Q) is:
True | |
Multi - Valued | |
Flase | |
Can not determined |
Question 2 Explanation:
We can also write (¬p → q) into (p ∨ q)
Here, we can minimize the boolean form into
¬p ∨ (p → q)
= ¬p ∨ (¬p ∨ q)
= ¬p ∨ q
In question, they are not discussed about the truth values of p, it implies that ¬p ∨ q also be True or False. So, we cannot be determined.
Here, we can minimize the boolean form into
¬p ∨ (p → q)
= ¬p ∨ (¬p ∨ q)
= ¬p ∨ q
In question, they are not discussed about the truth values of p, it implies that ¬p ∨ q also be True or False. So, we cannot be determined.
Question 3 |
Let A and B be two arbitrary events, then :
P(A∩B) = P(A) P(B) | |
P(P∪B) = P(A) + P(B) | |
P(A∪B) ≤ P(A) + P(B) | |
P(A / B) = P(A∩B) + P(B) |
Question 3 Explanation:
Option-A is happens when A and B are independent.
Option-B is happens when A and B are mutually exclusive.
Option-C is not happens.
Option-D is P(A∪B) ≤ P(A) + P(B) is true because P(A∪B) = P(A) + P(B) - P(A∩B).
Option-B is happens when A and B are mutually exclusive.
Option-C is not happens.
Option-D is P(A∪B) ≤ P(A) + P(B) is true because P(A∪B) = P(A) + P(B) - P(A∩B).
Question 4 |
Which sentence can be generated by
S→d/bA
A→d/ccA
S→d/bA
A→d/ccA
bccddd | |
aabccd | |
ababccd | |
abbbd | |
None of the above |
Question 4 Explanation:
Here, there is no terminal symbol ‘a’, so the answer never be option B,C,D.
Option-A is also wrong because the string generated by grammar is bccccd.
Option-A is also wrong because the string generated by grammar is bccccd.
Question 5 |
Regular expression a+b denotes the set :
{a} | |
{ε, a, b} | |
{a, b} | |
None of these |
Question 5 Explanation:
The regular expression a+b denotes the set {a, b}.
Question 6 |
Which of the following is divisible by 4 ?
100101100 | |
1110001110001 | |
11110011 | |
10101010101010 |
Question 6 Explanation:
Option-A: (100101100) 2 = (300) 10
300 is divisible by 4
Option-B: (1110001110001) 2 = (7281) 10
7281 is not divisible by 4
Option-C: (11110011) 2 = (243) 10
243 is not divisible by 4
Option-D: (10101010101010) 2 = (10,922) 10
10,922 is not divisible by 4.
300 is divisible by 4
Option-B: (1110001110001) 2 = (7281) 10
7281 is not divisible by 4
Option-C: (11110011) 2 = (243) 10
243 is not divisible by 4
Option-D: (10101010101010) 2 = (10,922) 10
10,922 is not divisible by 4.
Question 7 |
A half-adder is also known as :
AND Circuit | |
NAND Circuit | |
NOR Circuit | |
EX-OR Circuit |
Question 7 Explanation:
→ The half adder adds two single binary digits A and B. It has two outputs, sum (S) and carry (C). The carry signal represents an overflow into the next digit of a multi-digit addition. The value
of the sum is 2C + S. The simplest half-adder design incorporates an XOR gate for S and an AND gate for C. The Boolean logic for the sum (in this case S) will be A′B + AB′ whereas for the carry (C) will be AB.
Question 8 |
Consider the following sequence of instructions :
a=a⊕b, b=a⊕b, a=b⊕a
This Sequence
a=a⊕b, b=a⊕b, a=b⊕a
This Sequence
retains the value of the a and b | |
complements the value of a and b | |
swap a and b | |
negates values of a and b |
Question 8 Explanation:
⇒ a=a⊕b
⇒ b=a ⊕b
= a⊕b ⊕b (Substitute (1))
= 0 ⊕ b
= b
⇒ a = b⊕a
= b⊕a⊕b (Substitute (1))
= a⊕b⊕b
= a⊕0
= a
⇒ b=a ⊕b
= a⊕b ⊕b (Substitute (1))
= 0 ⊕ b
= b
⇒ a = b⊕a
= b⊕a⊕b (Substitute (1))
= a⊕b⊕b
= a⊕0
= a
Question 9 |
Consider the following circuit :
to make it a Tautology the ? should be :
to make it a Tautology the ? should be :
NAND gate | |
AND gate | |
OR gate | |
EX-OR gate |
Question 9 Explanation:
Method 1:
(X+Y) + (XY)’
= X+Y+X’+Y’
= (X+X’)+(Y+Y’)
= 1
Method 2:
(X+Y) + (XY)’
= X+Y+X’+Y’
= (X+X’)+(Y+Y’)
= 1
Method 2:
Question 10 |
When an inventor is placed between both inputs of an S-R flip flop, the resulting flip flop is :
JK flip-flop | |
D-flip-flop | |
T flip-flop | |
None of these |
Question 10 Explanation:
Given question is ambiguous. It is not mentioned how the inverter is connected. Placing NOT gate in different positions gives different solutions.
Question 11 |
What is the output of the following C-program
main()
{
printf(''%d%d%d'', sizeof(3.14f), sizeof(3.14), sizeof(3.141));
}
main()
{
printf(''%d%d%d'', sizeof(3.14f), sizeof(3.14), sizeof(3.141));
}
4 4 4 | |
4 8 10 | |
8 4 8 | |
8 8 8 | |
None of the above |
Question 11 Explanation:
The sizeof operator will print number of bytes of a data type.
sizeof(3.14f) → It will consider as float data type. The float data type size is 4 bytes.
sizeof(3.14) → It will consider as double data type. The double data type size is 8 bytes.
sizeof(3.141) → It will consider as double data type. The double data type size is 8 bytes.
Output= 4 8 8
Note: The exact size of each of these 3 types depends on the C compiler implementation (or) platform
sizeof(3.14f) → It will consider as float data type. The float data type size is 4 bytes.
sizeof(3.14) → It will consider as double data type. The double data type size is 8 bytes.
sizeof(3.141) → It will consider as double data type. The double data type size is 8 bytes.
Output= 4 8 8
Note: The exact size of each of these 3 types depends on the C compiler implementation (or) platform
Question 12 |
The bitwise OR of 35 with 7 in C will be :
35 | |
7 | |
42 | |
39 |
Question 12 Explanation:
Step-1: First we have to convert into binary numbers
(35) 10 = ( 0010 0011 ) 2
(7) 10 = (0000 0111) 2
Step-2: Perform OR operation on both binary numbers.
0010 0011
0000 0111
---------------
0010 0111
----------------
Step-3: Convert result into Decimal number
(0010 0111) 2 = (39) 10
(35) 10 = ( 0010 0011 ) 2
(7) 10 = (0000 0111) 2
Step-2: Perform OR operation on both binary numbers.
0010 0011
0000 0111
---------------
0010 0111
----------------
Step-3: Convert result into Decimal number
(0010 0111) 2 = (39) 10