Question

A system undergoes a state change from $1$ to $2$. According to the second law of thermodynamics, for the process to be feasible, the entropy change, $S_2-S_1$ of the system

• A. is positive or zero
• B. is zero
• C. can be positive, negative or zero
• D. is negative ro zero

Answer 1

The correct option is C can be positive, negative or zero

For the process to be feasible, the entropy change can be positive, negative or zero.
When entropy change,
$\left(\Delta S\right)>0$ i.e., Heat is added to the system
$\left(\Delta S\right)<0$ i.e., Heat is rejected from the system
$\left(\Delta S\right)=0$ i.e., Reversible adiabatic process