Question

The condition for a reaction to occur spontaneously is:

• A. $△H$ must be negative
• B. $△S$ must be negative
• C. $(△H-T△S)$ must be negative
• D. $(△H+T△S)$ must be negative

Answer 1

The correct option is C $(△H-T△S)$ must be negative

For a reaction to occur spontaneously $\Delta G$ must be negative.

But $\Delta G=\Delta H-T\Delta S$

$\Delta H-T\Delta S$ must be negative.

Hence, option C is correct.