Question

A reaction is non-spontaneous when:

• A. $\Delta H$ is +ve, $\Delta S$ is -ve
• B. both $\Delta H$ and $\Delta S$ are -ve
• C. $\Delta H$ is -ve and $\Delta S$ is +ve
• D. none of these

Answer 1

The correct option is A $\Delta H$ is +ve, $\Delta S$ is -ve

For any reaction to be non-spontaneous the value of change in Gibb's free energy should be positive.
Since, $\Delta G=\Delta H-T\Delta S$
So, the value of $\Delta G>0i.e.\text{value of}\Delta H>0\text{and value of}\Delta S<0$
Hence, answer is option A.