In thermodynamics, a process is called reversible when

Options

A. surroundings and system changes into each other
B. there is no boundary between system and surroundings
C. The surroundings are always in equilibrium with system
D. The system changes into the surroundings spontaneously

Answer

c

Explanation

During reversible process, the internal equilibrium is distrubed only infinitesimally small and in the limit, it is not disturbed at all. Thus system and surroundings remain in equilibrium.