Examine the following statements:
- 1.All colours are pleasant.
- 2.Some colours are pleasant.
- 3.No colour is pleasant.
- 4.Some colours are not pleasant.
Given that statement 4 is true, what can be definitely concluded?
Answer & explanation
Answer: (d) 1 is false.
'Some colours are not pleasant' is the exact contradictory of 'All colours are pleasant', so if statement 4 is true, statement 1 must be false. Statements 2 and 3 could go either way.
- Statement 4 (some colours are not pleasant) and statement 1 (all colours are pleasant) are contradictories: exactly one of them is true.
- 4 is true, so 1 is false — definitely.
- Statement 2 may or may not hold, because the remaining colours may or may not be pleasant; so 2 and 3 are both undetermined.
- Only (d) is certain.
- ✗ (a) 1 is false, so '1 and 2 are true' cannot hold.
- ✗ (b) 4 does not rule out some colours being pleasant, so 3 is not certain.
- ✗ (c) 2 may still be true — some colours can be pleasant while others are not.
- ✓ (d) 'Some … are not' is the contradictory of 'All … are'; when one is true, the other is false.
Remember · Contradictory pairs: All vs Some-not, and No vs Some. If one of a pair is true, the other is false; other pairs stay undetermined.
Question and answer: UPSC's official GS Paper II (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·