Four tests—Physics, Chemistry, Mathematics and Biology are to be conducted on four consecutive days, not necessarily in the same order. The Physics test is held before the test which is conducted after Biology. Chemistry is conducted exactly after two tests are held. Which is the last test held?
Answer & explanation
Answer: (c) Mathematics
Chemistry is on day 3. Biology cannot be last, since a test follows it, and cannot be first, since Physics must come before the test after Biology. So Biology is on day 2, Physics on day 1, and Mathematics is left for day 4.
- 'Exactly after two tests are held' puts Chemistry on day 3.
- Some test is held after Biology, so Biology is not on day 4.
- If Biology were on day 1, the test after it would be on day 2, and Physics would have to be on day 1 — already taken. So Biology is not on day 1.
- So Biology is on day 2; the test after it is Chemistry (day 3), and Physics is before that — day 1.
- Order: Physics, Biology, Chemistry, Mathematics. The last test is Mathematics.
Remember · Fix the absolute clue first (a definite day), then test the remaining slots against each relative clue.
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). ·