UGC NET Questions (Paper – 1)

Statements A, B and C correctly define tautology, contradiction and contingency by looking at truth across all valuations. Statement E is also true because the negation of a formula that is always true must be false on every valuation, hence a contradiction. Statement D is impossible in classical logic, since no statement can be both always true and always false at once. Therefore, the complete set of correct statements is A, B, C and E only, which matches option C.

Option A:
Option A is incomplete because it omits E and therefore fails to mention the important relationship between tautologies and contradictions via negation. It lists correct information but not the full set of true statements for this question.

Option B:
Option B is incorrect since it leaves out B and includes only A, C and E, ignoring the explicit definition of contradiction that is central to the topic. Without B the description of the three categories is not complete.

Option C:
Option C is correct as it brings together the accurate definitions of the three types of statements and the fact that the negation of a tautology is a contradiction, while excluding D, which suggests an incoherent situation in classical logic.

Option D:
Option D is wrong because it includes D, which falsely claims that a statement can be both tautology and contradiction and calls that “contingent”, and it omits A, so it both accepts a logical impossibility and loses a key correct statement.

Statements A and B correctly define tautology and contradiction, D states that truth tables are a systematic method to classify statements and E rightly explains that contingent statements are sometimes true and sometimes false. Statement C is false because it mistakenly assigns the property of tautology to contingent statements by saying they are true in all situations. Consequently, A, B, D and E together form the only correct combination.

Option A:
Option A is correct because it lists exactly the statements that match standard logical definitions and excludes C, which confuses contingency with tautology. It reflects the approach used in UGC NET when analysing compound statements.

Option B:
Option B is incomplete since it omits E and therefore does not describe how contingent statements behave across different truth assignments. Without E, the classification of logical status is less complete.

Option C:
Option C is wrong because it leaves out A and thereby fails to define tautology explicitly, while still not correcting the misstatement about contingency. Although some included statements are true, the set is not complete.

Option D:
Option D is incorrect because it includes C, the false description of contingent statements, and so mixes an error with otherwise true statements. That mixture makes the option logically inconsistent.

Statements A, B, D and E are correct, while C is false. A tautology is true under every valuation and a contradiction is false under every valuation. A contingent statement is true in some valuations and false in others, so C is incorrect. If a conclusion is a tautology, there is no possible case where premises are true and the conclusion is false, so the argument is valid regardless of premises (though it may be uninformative). Distinguishing these notions helps in validity checking in UGC NET, so E is also correct.

Option A:
Option A is incorrect because it omits D. Since D is true in classical logic, A, B, E only is incomplete.

Option B:
Option B is correct because it includes exactly the true statements A, B, D and E and excludes C, which misdefines contingency.

Option C:
Option C is wrong because it includes C, the false claim that a contingent statement is true in all valuations.

Option D:
Option D is wrong because it includes C (false) and omits B (true), so A, C, D, E only cannot be correct.

Statements A, B, C, E and F correctly distinguish tautologies, contradictions and contingencies and relate them to argument validity, while D is false. A tautological conclusion is always true, so any argument with such a conclusion is at least logically valid, though possibly uninformative. Contradictory premises render an argument vacuously valid because there is no case where all premises are true, and recognising logical status helps in judging equivalence and validity in exams. D is wrong because it asserts the opposite about tautological conclusions. Therefore A, B, C, E and F only is the correct combination.

Option A:
Option A is incomplete because it omits E and F, leaving out the role of contradictory premises and the exam-related significance of these distinctions. Although A, B and C are true definitions, they do not connect to argument validity. Thus this option is not complete.

Option B:
Option B is also incomplete, adding E but still omitting F, which summarises the practical usefulness of these categories in UGC NET. Without F, the option lacks an explicit link to reasoning tasks. Hence it cannot be the best answer.

Option C:
Option C is correct since it combines the basic definitions with a key fact about arguments from contradictions and the exam relevance of recognising logical status. It excludes D, which mischaracterises arguments with tautological conclusions. This makes the option logically consistent.

Option D:
Option D is incorrect because it includes D, thereby accepting the false view that tautological conclusions always make arguments invalid, and it omits A, the central definition of tautology. This combination cannot be taken as correct.