Question

Reversible processes are always _______ .

• A. Spontaneous
• B. Quasi-static
• C. Both a and b
• D. None of these

Answer 1

The correct option is B Quasi-static

Any reversible process is necessarily a quasi-static one. However, some quasi-static processes are irreversible, if there is heat flowing (in to or out of the system) or if entropy is being created in some other way. An example of a quasi-static process that is not reversible is a compression against a system with a piston subject to friction — although the system is always in thermal equilibrium, the friction ensures the generation of dissipative entropy, which directly goes against the definition of reversible.