Question

A system undergoes a reversible adiabatic process. The entropy of the system

• A. increases
• B. decreases
• C. remains constant
• D. may increase or may decrease

Answer 1

Answer: (C)

In general, the temperature of the system may change during a process. If the process is reversible, the change in entropy is defined as
$S_f-S_i={\int }_j^f\frac{\Delta Q}{T}$
In an adiabatic reversible process, no heat is given to the system. Therefore, entropy of the system remains constant in such a process.