JEE Chemistry 2025 Question with Solution

Given: The signs of $\Delta H$ and $\Delta S$ are listed with the stated temperature conditions for spontaneity.

Find: Which statements are correct.

Use the Gibbs free energy relation:

A reaction is spontaneous when $\Delta G < 0$.

Now check each case:

1. If $\Delta H > 0$ and $\Delta S < 0$, then both terms make $\Delta G$ positive. So the reaction is non-spontaneous at any temperature. This statement is correct.
2. If $\Delta H > 0$ and $\Delta S > 0$, the reaction becomes spontaneous at high temperature, not low temperature. So this statement is incorrect.
3. If $\Delta H < 0$ and $\Delta S < 0$, the reaction is spontaneous at low temperature. Therefore saying non-spontaneous at low temperature is incorrect.
4. If $\Delta H < 0$ and $\Delta S > 0$, both terms favor $\Delta G < 0$, so the reaction is spontaneous at any temperature. This statement is correct.

Therefore, the correct statements are (A) and (D), which corresponds to option B.

The solution also contains a conflicting line claiming option C, but the detailed Gibbs free energy analysis supports option B.