UGC NET Computer Science Unit 8 PYQs with Answers

UGC NET Computer Science Unit 8 is based on Database Management Systems (DBMS), one of the most scoring and concept-heavy areas of the syllabus. It deals with how data is structured, stored, retrieved, and managed efficiently using relational models and database techniques. 

Since questions are often conceptual as well as query-based, solving UGC NET Computer Science Unit 8 PYQs is extremely important. PYQs help candidates understand how topics like normalization, SQL, and transaction management are tested in the actual exam and highlight the most frequently asked concepts.

UGC NET Computer Science Unit 8 PYQs

UGC NET Computer Science Unit 8 Previous Year Questions (PYQs) primarily revolve around Database Management System concepts. This unit is particularly important because it combines conceptual clarity with direct application-based questions, making PYQ practice essential for scoring well.

1. Which of the following tasks could be attained using syntax trees in compiler design?

A. Type Checking
B. Code Generation
C. Code Optimisation
D. Error Handling

Choose the correct answer from the options given below:

A) A, B, C Only
B) B, C, D Only
C) A, C, D Only
D) A, B, D Only

Answer: A) A, B, C Only

Explanation: Syntax Trees (especially Abstract Syntax Trees - ASTs) are widely used in compiler design for:

• Type Checking (A): Semantic analysis uses syntax trees to verify type correctness.

• Code Generation (B): Target code can be generated by traversing the syntax tree.

• Code Optimization (C): Optimizations such as constant folding, dead code elimination, and expression simplification are often performed on syntax trees.

• Error Handling (D) is primarily associated with lexical, syntax, and semantic analysis phases rather than being a direct task attained using syntax trees.

2. Arrange the following stages of parsing in the correct order as they typically occur in the compilation process.

A. Lexical Analysis
B. Semantic Analysis
C. Syntax Analysis
D. Intermediate Code Generation
E. Code Optimization

Choose the correct answer from the options given below:

A) A, B, C, D, E
B) A, C, B, D, E
C) A, D, B, C, E
D) A, C, D, B, E

Answer: B) A, C, B, D, E

Explanation:

The standard compilation phases occur in the following order:

1. Lexical Analysis (A)

• Converts source code into tokens.

2. Syntax Analysis (C)

• Builds parse tree / syntax tree according to grammar rules.

3. Semantic Analysis (B)

• Performs type checking, scope checking, and other semantic validations.

4. Intermediate Code Generation (D)

• Produces an intermediate representation (IR).

5. Code Optimization (E)

• Improves the intermediate code for efficiency.

Thus, the correct sequence is: A → C → B → D → E

3. Which of the following tasks could be attained using syntax trees in compiler design?

A. Type Checking
B. Code Generation
C. Code Optimization
D. Error Handling

Choose the correct answer from the options given below:

A. A, B, C Only
B. B, C, D Only
C. A, C, D Only
D. A, B, D Only

Answer: A. A, B, C Only

Explanation: Syntax Trees (or Abstract Syntax Trees - ASTs) are widely used in compiler design for:

• Type Checking during semantic analysis.

• Code Generation by translating tree structures into target code.

• Code Optimization by simplifying expressions and improving efficiency.

Error handling is generally performed during lexical, syntax, and semantic analysis phases rather than being a direct function of syntax trees.

4. Shift-Reduce conflicts are resolved by:

A. Left recursion
B. Left factoring
C. Ambiguity
D. Associativity and Precedence

Answer: D. Associativity and Precedence

Explanation:
A Shift-Reduce Conflict occurs when a parser cannot decide whether to shift the next input symbol or reduce the current symbols on the stack. Such conflicts are commonly resolved using:

• Operator Precedence

• Operator Associativity (left-to-right or right-to-left)

5. Match List-I with List-II:

Choose the correct answer from the options given below:

A. A–IV, B–III, C–I, D–II
B. A–III, B–I, C–II, D–IV
C. A–II, B–IV, C–III, D–I
D. A–IV, B–III, C–II, D–I

Answer: A. A–IV, B–III, C–I, D–II

Explanation:

• A → aB | a represents a Right Linear Grammar, equivalent to Finite Automata (IV).

• A → BC | a is the form used in Chomsky Normal Form (III).

• LL(1) Grammar is parsed using a Recursive Descent Parser (I).

• The Halting Problem is associated with Turing Machines (II).

6. Which of the following is the function of the semantic analysis phase of the compilation process?

A. Type conversion
B. Tokenization
C. Loop optimization
D. Data flow Analysis

Answer: A. Type conversion

Explanation: The Semantic Analysis phase checks the meaning of the program, including Type checking, Type conversion/coercion, Scope resolution, and Declaration checking.

Other options belong to different phases:

• Tokenization → Lexical Analysis

• Loop Optimization → Code Optimization

• Data Flow Analysis → Optimization phase

7. One of the purposes of using intermediate code in compilers is to:

A. make parsing and semantic analysis simpler
B. improve error recovery and error reporting
C. increase the chances of reusing the machine independent optimizer in other compilers
D. improve the register allocation

Answer: C. increase the chances of reusing the machine independent optimizer in other compilers

Explanation: Intermediate Code Representation (IR) provides a machine-independent form of the source program. Its advantages include:

• Portability across different target machines.

• Reusability of machine-independent optimizers.

• Separation of front-end and back-end compiler phases.

8. Three address codes can be represented in special structures known as:

A. Quadruples
B. Triples
C. Patterns
D. Indirect Triples
Choose the correct answer from the options given below:

• A) A and B Only

• B) A, B and D Only

• C) B and C Only

• D) B, C and D Only

Answer: B) A, B and D Only
Explanation: Three address codes can be represented using Quadruples, Triples, and Indirect Triples — these are the three standard data structures used in compiler design for intermediate code representation. "Patterns" is not a valid representation structure for three address codes.