AIPMT PRELIMS2012Physics-Thermodynamics
AIPMT PRELIMS 2012 Physics Entropy and Gibbs Free Energy MCQ Question
Type: MCQ-conceptual-Medium-Class 11
In which of the following reactions, standard reaction entropy change (ΔS°) is positive and standard Gibb’s energy change (ΔG°) decreases sharply with increasing temperature?
A
1/2 C graphite + 1/2 Ω₂(g) → 1/2 CO₂(g)
B
C graphite + 1/2 Ω₂(g) → CO(g)
C
CO(g) + 1/2 Ω₂(g) → CO₂(g)
D
Mg(s) + 1/2 Ω₂(g) → MgO(s)
Correct Answer
Option B
Detailed Explanation
The reaction C graphite + 1/2 Ω₂(g) → CO(g) has a positive ΔS° because it involves the formation of a gas from a solid. The ΔG° decreases sharply with increasing temperature due to the positive entropy change.
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