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Topic Thermodynamics
Asked 11 times across 5 UPSC exams over 40 years (1986–2026), peaking in 2026.
Key insights
- Most tested in CDS — 4 of 11 PYQs
- Most asked in 2026
- Recurs across 8 years (1986–2026)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1986 → CDS 2017 → CAPF 2020 → GEO 2024 → NDA 2025
How the concept evolved
Rising — more than half its appearances (10 of 11) are since 2016.
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.
CDS2026
Which one of the following gives the triple point of water ?
- A Temperature 273·16 K and Pressure 1 Pa
- B Temperature 273·16 K and Pressure 6·11 × 10⁻³ Pa
- C Temperature 0 K and Pressure 10² Pa
- D Temperature 373 K and Pressure 6·11 × 10⁻³ Pa
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
NDA2026
A solid of mass m has temperature-dependent specific heat as C(T) = C₀ + αT, where C₀ and α are constants. The solid is heated from T₁ to T₂. Which one of the following is the correct expression for quantity of heat (Q) of the solid mass?
- A Q = mC₀(T₂ − T₁)
- B Q = m(T₂ − T₁)[C₀ + α(T₁ + T₂)]
- C Q = m(T₂ − T₁)[C₀(T₁ + T₂) + α]
- D Q = m(T₂ − T₁)[C₀ + (α/2)(T₁ + T₂)] ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
NDA2026
In a certain process, the relation between pressure (P) and volume (V), for an ideal gas, is given by PV² = constant. If the initial temperature is T₂ and the final temperature is T₂, and the initial volume is V₁ and the final volume is V₂, then which one of the following is correct?
- A T₁/T₂ = V₁/V₂
- B T₁/T₂ = (V₁/V₂)²
- C T₁/T₂ = V₂/V₁ ✓
- D T₁/T₂ = (V₂/V₁)²
✓ Correct answer: (C)
Science & Technology › Physics & Chemistry
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