Topic Gas laws
Asked 3 times across 2 UPSC exams over 46 years (1979–2025), peaking in 1979.
Key insights
- Most tested in CSE — 2 of 3 PYQs
- Most asked in 1979
- Recurs across 3 years (1979–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1979 → CISF 2025
How the concept evolved
Long-running — most appearances (2 of 3) predate 2016, and it still returns.
Related concepts
Ideas UPSC tests alongside this one — keep exploring.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
CISF2025
If the volume of a fixed mass of an ideal gas is halved at a constant temperature, the pressure inside the container would :
- A be doubled ✓
- B be halved
- C remain the same
- D be one-fourth
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
CSE1994
If a gas is compressed to half of its original volume at 27°C, to what temperature should it be heated to make it occupy its original volume?
- A 327°C ✓
- B 600°C
- C 54°C
- D 300°C
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
CSE1979
One litre of cold air weighs heavier than the dry air ( 1 Lit) because of the
- A Increased number of collisions between the molecules
- B Increased number of molecules at low temperature ✓
- C Greater energy of molecules at high temperature
- D Lower energy of molecules at high temperature
✓ Correct answer: (B)
Science & Technology › Physics & Chemistry
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