Project ForgeThermodynamics
Entropy & Second Law
GATE 2018
Easy
For an ideal gas with constant properties undergoing a quasi-static process, which one of the following represents the change of entropy (Δs) from state 1 to 2?
- Δs = Cp ln(T2/T1) − R ln(P2/P1)
- BΔs = Cv ln(T2/T1) − Cp ln(V2/V1)
- CΔs = Cp ln(T2/T1) − Cv ln(P2/P1)
- DΔs = Cv ln(T2/T1) + R ln(V1/V2)
Explanation
The standard entropy-change relation for an ideal gas in terms of temperature and pressure is Δs = Cp ln(T2/T1) − R ln(P2/P1), derived from Tds = dh − vdp and the ideal gas law.
Source: GATE ME 2018 Session 2 (Set 2) (2018)
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