Question

The spontaneity means, having the potential to proceed without the assistance of external agency. The process which occur spontaneously are

• A. Burning carbon in oxygen to give carbon dioxide
• B. Flow of heat from colder to warmer body
• C. Gas in a container contracting into one corner
• D. Gas expanding to fill the available volume.

Answer 1

Answer: (A), (D)

Gas expanding to fill the available volume.

Spontaneous processes are those processes which once started continue to occur on their own without any help of an external agency.

Option(A): is non-spontaneous because heat spontaneously flow from higher temprature to lower but vice-versa is non-spontaneous.
Option (B): is also non-spontaneous because gas cannot contract on its own without some external pressure applied.

Option(C):
Gas expanding in the entire available volume is spontaneous because gas moves from high pressure to low pressure on its own. Expansion leads to lowering of pressure of gas.

Option(D):
Carbon can spontaneously react with $O_2$ in the air to form $C{O}_2$.
Hence, option (C) and (D) are the correct.