Correct Answer - Option 1 : 0
Explanation:
Adiabatic process:
When a thermodynamic system undergoes a change in such a way that no exchange of heat takes place between the system and surrounding, the process is known as an adiabatic process.
Entropy (S):
It is a measure of the disorder of the molecular motion of a system.
Greater is the disorder, greater is the entropy.
The change in entropy is,
\({\rm{\Delta }}S = \frac{{{\rm{\Delta }}Q}}{T}\)
Where, ΔQ = Heat exchange, T = temperature of the system
- Entropy remains constant in an adiabatic process which is also reversible.
- For the sake of simplicity consider the case of a closed system, i.e. a control mass, which does not exchange any mass with the surroundings.
- There are two ways in which the entropy of such a system can change, firstly through heat transfer at the system boundary and secondly through entropy generation inside the system.
- Now the process is adiabatic, so the heat transfer is zero and so the entropy change is zero through heat transfer.
- Also, the process is reversible, so there is no entropy generated inside the system and the entropy change due to entropy generation is zero.
- In this way, the entropy change is zero for an adiabatic process which is also reversible.
For a reversible adiabatic process
\(dS = \frac{{dQ}}{T} = 0\)
