Identify the correct statement regarding a spontaneous process:

Options

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

Answer

C

Explanation

In an isolated system, there is no exchange of energy or matter between the system and surrounding . For a spontaneous process in an isolated system, the change in entropy is positive , i.e. `DeltaS gt 0.` Most of the spontaneous chemical reactions are exothermic . A number of endothermic reaction are spontaneous e.g. melting of ice (an endothermic process) is a spontaneous reaction. The two factors which are responsible for the spontaneity of process are
(i) tendency to acquire minimum energy
(ii) tendency to acquire maximum randomness.