UPSC Prelims 2020 · CSAT
Question 78: Basic Numeracy
If 1 litre of water weighs 1 kg, then how many cubic millimetres of water will weigh 0·1 gm?
AnswerUPSC’s answer is (c).
1 litre = 1,000 cm³ weighs 1 kg = 1,000 g, so 1 cm³ of water weighs 1 g. So 0.1 g occupies 0.1 cm³. Since 1 cm³ = 1,000 mm³ (10 × 10 × 10), 0.1 cm³ = 100 mm³. Remember the cube: 10 mm per cm, so 1,000 mm³ per cm³.
How you could have got this
No shortcut here: in a “how many” question, ruling out options doesn’t help. Every statement has to be judged.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) 1 mm³ weighs 0.001 g.
- (b) 10 mm³ weighs 0.01 g.
- (c) Right: 100 mm³ weighs 0.1 g.
- (d) 1,000 mm³ weighs 1 g.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2020, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.