Q. Let us consider an endothermic reaction which is non-spontaneous at the freezing point of water. However, the reaction is spontaneous at boiling point of water. Choose the correct option.
A) Both $\Delta H$ and $\Delta S$ are (-ve)
B) $\Delta H$ is (-ve) but $\Delta S$ is (+ve)
C) $\Delta H$ is (+ve) but $\Delta S$ is $(-ve)$
D) Both $\Delta H$ and $\Delta S$ are (+ve)
Explanation
[Solution by Dr. Abubacker] Endothermic means $\Delta H>0$. $\Delta G=\Delta H-T\Delta S$ is positive at low $T$ and negative at high $T$ only if $\Delta S>0$. So both are positive. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.