Q153 · CSIR-NET Chemistry, December 2019
Paper: CSIR-NET December 2019 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Laws State Functions · Marks: 2 · Difficulty: Medium
Consider the entropy changes in a system undergoing transformation, as depicted in the diagram, below 
The correct statement among the following is (1) $\Delta \mathrm{S}_{1}=\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S} \neq \Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ (2) $\Delta \mathrm{S}_{1}>\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S} \neq \Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ (3) $\Delta \mathrm{S}_{1}=\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S}=\Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ (4) $\Delta \mathrm{S}_{1}>\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S}=\Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ Options
The correct statement among the following is (1) $\Delta \mathrm{S}_{1}=\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S} \neq \Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ (2) $\Delta \mathrm{S}_{1}>\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S} \neq \Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ (3) $\Delta \mathrm{S}_{1}=\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S}=\Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ (4) $\Delta \mathrm{S}_{1}>\Delta \mathrm{S}_{2}$ and $\Delta \mathrm{S}=\Delta \mathrm{S}_{1}+\Delta \mathrm{S}_{2}$ Options(a)1
(b)2
(c)3
(d)4
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
ΔS₁ = C_p ln(323/298) > ΔS₂ = C_p ln(348/323), and since S is a state function ΔS = ΔS₁ + ΔS₂ — statement (4).
Study loop for Thermodynamics