UGC NET Questions (Paper – 1)

Statements A, B, D and E are correct, whereas C and F are false. Simple statements have no smaller statement parts, and compound statements are built from them with connectives. Negation does flip truth values in classical logic, and each atomic statement gets its own column in a truth table. C is wrong because connectives also determine how component truth values combine, and F is wrong because UGC NET questions frequently use compound statements.

Option A:
Option A is incorrect because it leaves out statement E, which accurately describes how truth tables are constructed. While A, B and D are true, omitting E means the answer does not include all correct statements. The description of truth-table practice is therefore incomplete in this option.

Option B:
Option B is correct since it brings together A, B, D and E, the four statements that match standard propositional logic. It excludes C, which ignores the role of connectives, and F, which falsely denies the presence of compound statements in exam questions. This combination therefore reflects both theory and examination practice.

Option C:
Option C is wrong because it includes C along with otherwise correct statements. C claims that connectives do not matter for truth values, which contradicts the whole idea of truth-functional operators. Adding a false statement makes the entire combination unacceptable.

Option D:
Option D is incorrect because it omits A, the basic definition of a simple statement, and it starts from B. Although B, D and E are true, without A the picture of the distinction between simple and compound statements is incomplete. Thus this option fails to represent the full set of correct statements.

Statements A, B and D all accurately describe biconditional statements. A gives the overall truth condition: both sides must match in truth value. B shows that “if and only if” can be written as the conjunction of two implications. D restates the falsity condition: the biconditional fails when P and Q differ in truth. C is false because “P or Q” is true in more cases than “P if and only if Q”, and E is false because biconditionals are not tautologies. Hence A, B and D only are correct.

Option A:
Option A is incomplete because it omits D, so it fails to mention explicitly when the biconditional is false, which is essential for constructing its truth table.

Option B:
Option B is incorrect as it includes only B and D and omits A, losing the succinct characterisation that biconditional is true exactly when P and Q agree.

Option C:
Option C is wrong because it adds E, which incorrectly asserts that biconditionals are always true, and it therefore includes at least one false statement.

Option D:
Option D is correct as it brings together the equivalence in terms of matching truth values, the conjunction of implications and the falsity condition, while excluding C and E, which misrepresent the biconditional.

Statements A and B restate De Morgan’s laws, showing how negation distributes over “and” and “or”, C correctly defines logical equivalence in terms of matching truth values and D is true because De Morgan’s laws explicitly connect conjunction, disjunction and negation. Statement E is false since contradictory statements cannot both be true in any possible situation; one must be false whenever the other is true. Hence, the combination A, B, C and D only is correct.

Option A:
Option A is incomplete because, although it lists three true statements, it omits D and thus does not explicitly say that De Morgan’s laws are the ones relating “and”, “or” and “not”. Without D, the named connection between these operators is not emphasised.

Option B:
Option B is also incomplete because it leaves out A and thereby fails to include the first De Morgan equivalence concerning the negation of “p and q”. That omission makes the description of the laws partial.

Option C:
Option C is correct as it bundles all four true statements, fully describing De Morgan’s laws and logical equivalence, while rejecting E, which mischaracterises contradictions. It aligns with the logical tools used in UGC NET reasoning.

Option D:
Option D is wrong because it includes E, the false statement about contradictions, and omits C, the formal definition of logical equivalence. This combination mixes error with omission.

All five statements A through E are correct descriptions of standard logical classifications and their exam use. Tautologies are true under all assignments, contradictions are always false, and contingencies vary with the assignment. A statement and its negation cannot both be tautologies because their truth-values must differ somewhere. Recognising tautological patterns is useful in UGC NET for spotting valid argument forms.

Option A:
Option A is incomplete because it omits E, missing the applied exam-use point.

Option B:
Option B is correct since it includes every true statement (A–E).

Option C:
Option C is wrong because it omits C (definition of contingency).

Option D:
Option D is incorrect because it omits A (definition of tautology).