Question

Identify the correct statement regarding a spontaneous process.

• A. Lowering of energy in the process is the only criterion for spontaneity.
• B. For a spontaneous process in an isolated system, the change in entropy is positive.
• C. Endothermic process are never spontaneous.
• D. Exothermic process are always spontaneous.

Answer 1

The correct option is B For a spontaneous process in an isolated system, the change in entropy is positive.

In an isolated system, energy remains constant.

$\therefore$ Driving force for a spontaneous process will be to increase entropy.

Therefore, the change in entropy is positive.

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

$\Delta H=0$ for an isolated system.

$-\Delta G=T\Delta S$

$\Delta G<0$ for a spontaneous process.

$\therefore \Delta S>0$ for a spontaneous process.