Question

Which of the following conditions are correct? A. $\Delta H$ is +ve, $\Delta S$ is -ve at any T (non-spontaneous). B. $\Delta H$ is -ve, $\Delta S$ is -ve at low T (non-spontaneous). C. $\Delta H$ is +ve, $\Delta S$ is +ve at low T (spontaneous). D. $\Delta H$ is -ve, $\Delta S$ is +ve at any T (spontaneous).

• A. C, D only
• B. A, B, C only
• C. B, C only
• D. A, D only

Hint:

If the universe gets messier ($\Delta S > 0$) and the system loses heat ($\Delta H < 0$), it's always spontaneous!

Answer 1

The Correct Option is D

Step 1: Concept Spontaneity is determined by the Gibbs Free Energy equation: $\Delta G = \Delta H - T\Delta S$. A process is spontaneous if $\Delta G < 0$.

Step 2: Meaning Condition A: $\Delta H(+), \Delta S(-)$ makes $\Delta G$ always positive (non-spontaneous). Correct. Condition D: $\Delta H(-), \Delta S(+)$ makes $\Delta G$ always negative (spontaneous). Correct.

Step 3: Analysis Condition B: $\Delta H(-), \Delta S(-)$ makes $\Delta G$ negative at low temperatures, making it spontaneous (not non-spontaneous). Condition C: $\Delta H(+), \Delta S(+)$ requires high temperature for $\Delta G$ to be negative; it is non-spontaneous at low T.

Step 4: Conclusion Statements A and D are the only accurate thermodynamic descriptions provided. Final Answer: (D)