UPSC Prelims 1995 · General Studies
Question 82: Logical Reasoning and Mental Ability
Examine the following statements: I. All children are inquisitive. II. Some children are inquisitive. III. No children are inquisitive. IV. Some children are not inquisitive. Among these statements, the two statements which cannot both be true simultaneously but can both be false would be
AnswerThe answer is (a).
Statements I and III are contraries: 'all children are inquisitive' and 'no children are inquisitive' cannot both be true, but both are false if some children are inquisitive and some are not. The other pairs behave differently: I and IV contradict each other, so exactly one is true, as do II and III, while III and IV can both be true.
Why each option is right or wrong
- (a) Right: contraries, which cannot both be true but can both be false.
- (b) I and IV are contradictories: exactly one is true, so they cannot both be false.
- (c) II and III are contradictories, so they cannot both be false.
- (d) III and IV can both be true, for instance when no child is inquisitive.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1995, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.