A spontaneous reaction is impossible if

Options

A. both `DeltaH` and `DeltaS` are negative
B. both `DeltaH` and `DeltaS` are positive
C. `DeltaH` is negative and `DeltaS` is positive
D. `DeltaH` is positive and `DeltaS` is negative

Answer

D

Explanation

For a reaction to be non-spontaneous, `DeltaG gt 0`. It can happen when both `DeltaH` and `DeltaS` are unfavourable i.e., when `DeltaH` is `+ve` and `DeltaS` is `-ve`