UGC NET Computer Science MCQs 2026: 50 Important Questions with Answers

UNIT 1 — Discrete Structures & Optimization

Q1.

Let $p,q,r$ be propositions. Which of the following is logically equivalent to

p \rightarrow (q \rightarrow r)

A. $(p\land q)\rightarrow r$
B. $(p\lor q)\rightarrow r$
C. $p\rightarrow(q\land r)$
D. $(p\rightarrow q)\rightarrow r$

Answer: A

Explanation:

p\rightarrow(q\rightarrow r) \equiv \neg p\lor(\neg q\lor r) \equiv \neg(p\land q)\lor r

Hence,

(p\land q)\rightarrow r

Q2.

A connected undirected graph has exactly four vertices of odd degree. Which statement is necessarily true?

A. It has an Euler circuit
B. It has an Euler path but not an Euler circuit
C. It has neither an Euler path nor an Euler circuit
D. It must be a Hamiltonian graph

Answer: C

Explanation:
An undirected connected graph has an Euler path iff it has exactly 0 or 2 odd-degree vertices. Four odd-degree vertices means neither Euler path nor Euler circuit.

Q3.

A relation $R$ on a set $A$ is reflexive, antisymmetric and transitive. Then $R$ is:

A. Equivalence relation
B. Partial order relation
C. Total order relation
D. Symmetric relation

Answer: B

Q4.

Suppose a graph has chromatic number 3. Which of the following must be true?

A. It contains a triangle
B. It is not bipartite
C. Every vertex has degree at least 3
D. It contains an odd cycle of length 3

Answer: B

Explanation:
A graph is bipartite iff it is 2-colourable. Therefore a graph requiring 3 colours cannot be bipartite.

It need not contain a triangle; an odd cycle such as $C_5$ has chromatic number 3.

Q5.

In a linear programming problem, if the feasible region is non-empty and bounded, then:

A. An optimal solution cannot exist
B. An optimal solution always exists
C. Only an integer solution exists
D. The objective function must be constant

Answer: B

UNIT 2 — Computer System Architecture

Q6.

Consider a 32-bit processor with a cache having $2^{10}$ cache lines. Each cache line contains 64 bytes. For a direct-mapped cache, the number of bits required for the index field is:

A. 6
B. 10
C. 16
D. 32

Answer: B

Explanation:
Number of cache lines:

2^{10}

Therefore index bits = 10.

Q7.

Which memory technology normally requires periodic refreshing?

A. SRAM
B. DRAM
C. ROM
D. Flash memory

Answer: B

Q8.

Which of the following is not a characteristic of RISC architecture?

A. Large register set
B. Simple instructions
C. Fixed-length instructions are common
D. Large number of complex addressing modes

Answer: D

Q9.

A processor uses a 5-stage pipeline. If 100 instructions are executed and there are no stalls, the number of clock cycles required is:

A. 100
B. 104
C. 105
D. 500

Answer: B

For a $k$ -stage pipeline:

k+n-1

=5+100-1=104

Q10.

Which addressing mode is particularly useful for accessing elements of an array?

A. Immediate
B. Register
C. Indexed
D. Implied

Answer: C

UNIT 3 — Programming Languages & Computer Graphics

Q11.

Which parameter-passing mechanism allows the called procedure to modify the caller's actual parameter directly?

A. Call by value
B. Call by reference
C. Call by name
D. Pass by result

Answer: B

Q12.

Consider the following C declaration:

int (*p)[10];

What does p represent?

A. Pointer to an integer
B. Array of 10 integer pointers
C. Pointer to an array of 10 integers
D. Function returning pointer to integer

Answer: C

Q13.

Which parsing technique is a bottom-up parsing technique?

A. Recursive descent
B. LL(1)
C. LR
D. Predictive parsing

Answer: C

Q14.

In computer graphics, homogeneous coordinates are primarily useful for:

A. Eliminating rasterization
B. Representing transformations such as translation using matrix multiplication
C. Increasing colour depth
D. Reducing image resolution

Answer: B

Q15.

Which transformation preserves both distances and angles?

A. Translation
B. Rotation
C. Scaling
D. Shearing

Answer: B

Note: Uniform scaling preserves angles but not distances, while rotation is a rigid transformation.

UNIT 4 — DBMS

Q16.

Consider relation:

R(A,B,C,D)

with functional dependencies:

A\rightarrow B,\quad B\rightarrow C,\quad C\rightarrow D

The candidate key is:

A. A
B. B
C. C
D. D

Answer: A

Because:

A^+=\{A,B,C,D\}

Q17.

Which normal form specifically eliminates transitive dependency of non-prime attributes on candidate keys?

A. 1NF
B. 2NF
C. 3NF
D. 4NF

Answer: C

Q18.

Which SQL operation is primarily used to combine rows from two relations based on a matching condition?

A. UNION
B. JOIN
C. INTERSECT
D. DIFFERENCE

Answer: B

Q19.

Which concurrency-control protocol guarantees conflict serializability by imposing an ordering on transactions?

A. Timestamp ordering
B. Two-phase locking
C. Both A and B
D. Deadlock prevention only

Answer: C

Q20.

In a B+ tree:

A. Records are stored only in internal nodes
B. Records/data pointers are generally stored at leaf nodes
C. Leaf nodes cannot be linked
D. Internal nodes always contain complete records

Answer: B

UNIT 5 — System Software & Operating System

Q21.

Which scheduling algorithm can suffer from the convoy effect?

A. Round Robin
B. FCFS
C. SRTF
D. Priority scheduling only

Answer: B

Q22.

Consider three processes:

Process	Arrival	Burst
P1	0	8
P2	1	4
P3	2	2

Under non-preemptive FCFS, the average waiting time is:

A. 3.67
B. 4.33
C. 5.67
D. 6.00

Answer: B

Execution:

P1: 0–8
P2: 8–12
P3: 12–14

Waiting times:

P1 = 0
P2 = 7
P3 = 10

Average=\frac{0+7+10}{3}=5.67

Correction: Therefore the correct answer is C.

This is exactly the kind of calculation where careless reading produces a wrong answer.

Answer: C

Q23.

Which condition is not one of Coffman's necessary conditions for deadlock?

A. Mutual exclusion
B. Hold and wait
C. Circular wait
D. Starvation

Answer: D

Q24.

A page fault occurs when:

A. A page is present in the TLB
B. A referenced page is not currently in main memory
C. The CPU cache misses
D. The process terminates

Answer: B

Q25.

Which page replacement algorithm can exhibit Belady's anomaly?

A. LRU
B. Optimal
C. FIFO
D. MRU

Answer: C

UNIT 6 — Software Engineering

Q26.

Which software development model is most appropriate when requirements are expected to evolve through repeated customer feedback?

A. Pure Waterfall
B. Iterative/Incremental model
C. Big Bang model
D. Code-and-Fix model

Answer: B

Q27.

If a module has high cohesion and low coupling, it generally indicates:

A. Poor modularity
B. Good software design
C. High maintenance cost
D. Strong dependency between modules

Answer: B

Q28.

Which testing technique examines the internal logic and structure of the program?

A. Black-box testing
B. White-box testing
C. Acceptance testing
D. Beta testing

Answer: B

Q29.

A software system has 5 modules. If every module directly communicates with every other module, the number of communication links is:

A. 5
B. 10
C. 15
D. 20

Answer: B

\frac{5(5-1)}{2}=10

This illustrates why excessive coupling becomes problematic as system size increases.

Q30.

Which metric is directly associated with the number of independent paths in a program's control-flow graph?

A. Function point
B. Cyclomatic complexity
C. Halstead length
D. LOC

Answer: B

UNIT 7 — Computer Networks

Q31.

Which protocol is primarily responsible for reliable, connection-oriented transport?

A. IP
B. UDP
C. TCP
D. ARP

Answer: C

Q32.

A network uses IPv4 address:

192.168.10.0/26

How many usable host addresses are available per subnet?

A. 62
B. 64
C. 126
D. 254

Answer: A

Host bits:

32-26=6

Total addresses:

2^6=64

Usable:

64-2=62

Q33.

Which protocol resolves an IPv4 address into a MAC address on a local network?

A. DNS
B. ARP
C. DHCP
D. ICMP

Answer: B

Q34.

Which routing algorithm is associated with the distance-vector approach?

A. Dijkstra
B. Bellman-Ford
C. Prim
D. Kruskal

Answer: B

Q35.

Which statement about UDP is correct?

A. It guarantees ordered delivery
B. It provides congestion control
C. It is connectionless
D. It retransmits lost packets automatically

Answer: C

UNIT 8 — Theory of Computation

Q36.

Which class of languages is accepted by a finite automaton?

A. Context-sensitive languages
B. Context-free languages
C. Regular languages
D. Recursively enumerable languages

Answer: C

Q37.

Which of the following is not closed under regular languages?

A. Union
B. Intersection
C. Complement
D. None of the above

Answer: D

Regular languages are closed under all three.

Q38.

Which machine is equivalent in computational power to a deterministic finite automaton?

A. Pushdown automaton
B. NFA
C. Turing machine
D. Linear bounded automaton

Answer: B

Q39.

The language

L=\{a^n b^n\mid n\geq0\}

is:

A. Regular
B. Context-free but not regular
C. Context-sensitive but not context-free
D. Not recursively enumerable

Answer: B

Q40.

Which problem is known to be undecidable?

A. DFA membership
B. CFG membership
C. Turing machine halting problem
D. Regular expression matching

Answer: C

UNIT 9 — Artificial Intelligence

Q41.

Which search algorithm is guaranteed to find an optimal solution when the heuristic is admissible and appropriate conditions hold?

A. DFS
B. Greedy best-first search
C. A*
D. Hill climbing

Answer: C

Q42.

A heuristic $h(n)$ is admissible if:

A. It always overestimates the true cost
B. It never overestimates the true cost
C. It is always zero
D. It equals the exact cost for every node

Answer: B

Q43.

Which learning paradigm uses labelled training examples?

A. Unsupervised learning
B. Reinforcement learning
C. Supervised learning
D. Self-organizing learning

Answer: C

Q44.

Which activation function is most commonly associated with the vanishing-gradient problem in deep networks?

A. ReLU
B. Sigmoid
C. Linear
D. Step

Answer: B

Q45.

In a minimax game tree, an optimal MAX player attempts to:

A. Minimize its utility
B. Maximize its utility assuming the opponent also plays optimally
C. Randomly select a move
D. Always choose the shallowest node

Answer: B

UNIT 10 — Data Mining, Big Data & Emerging Technologies

Q46.

In association-rule mining, support of $X\rightarrow Y$ is:

A. $P(Y|X)$
B. $P(X\cup Y)$
C. $P(X)/P(Y)$
D. $P(X-Y)$

Answer: B

Q47.

If:

support(X\cup Y)=0.30

and

support(X)=0.50

then the confidence of $X\rightarrow Y$ is:

A. 0.15
B. 0.30
C. 0.60
D. 0.80

Answer: C

Confidence=\frac{support(X\cup Y)}{support(X)}

= \frac{0.30}{0.50} = 0.60

Q48.

Which characteristic is not traditionally included among the three Vs of Big Data?

A. Volume
B. Velocity
C. Variety
D. Verification

Answer: D

Q49.

Which technique is primarily used to reduce the dimensionality of a dataset while preserving maximum variance?

A. K-means
B. PCA
C. Apriori
D. Naive Bayes

Answer: B

Q50.

Consider the following statements about machine learning:

S1: Increasing model complexity can reduce training error.

S2: Increasing model complexity always reduces test error.

S3: Overfitting occurs when a model captures noise/specificities of training data and performs poorly on unseen data.

Which is correct?

A. S1 only
B. S1 and S2 only
C. S1 and S3 only
D. S1, S2 and S3

Answer: C

S2 is false because increasing complexity can eventually increase generalization/test error

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