Easy MCQ +4 / -1 PYQ · JEE Mains 2025

Let us consider a reversible reaction at temperature, T. In this reaction, both $\Delta \mathrm{H}$ and $\Delta \mathrm{S}$ were observed to have positive values. If the equilibrium temperature is Te , then the reaction becomes spontaneous at:

  1. A $\mathrm{Te}>\mathrm{T}$
  2. B $\mathrm{T}>\mathrm{Te}$ Correct answer
  3. C $\mathrm{T}=\mathrm{Te}$
  4. D $\mathrm{Te}=5 \mathrm{~T}$

Solution

<p>For reaction to be spontaneous according to $2^{\text {nd }}$ law:</p> <p>$$\begin{aligned} & \Delta \mathrm{G}<0 \\ & \Rightarrow \Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{~S}<0 \\ & \Rightarrow \mathrm{~T}>\left(\frac{\Delta \mathrm{H}}{\Delta \mathrm{~S}}\right)=\mathrm{T}_{\mathrm{e}} \\ & \Rightarrow \mathrm{~T}>\mathrm{T}_{\mathrm{e}} \end{aligned}$$</p>

About this question

Subject: Chemistry · Chapter: Thermodynamics · Topic: Zeroth and First Law

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