The spotanity means having the potential to proceed without assistance of external agency. The processess which occur spontaneously are

Options

A. flow of heat from colder to warmer body
B. gas in a container contracting into one corner
C. gas expanding to fill the available volume
D. burining carbon in oxygen to given carbon dioxide

Answer

C, D

Explanation

Gas expands of diffuses in availabel space spontaneously, e.g., leakage of cooling gas gives smell of ethyl mercapatan spontaneously.
Moreover burning of carbon to `CO_(2)` is also spontaneous