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

Options

A. Remains constant
B. May increase or may decrease
C. Increases
D. Decreases

Answer

To solve the question about the entropy of a system undergoing a reversible adiabatic process, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process**: Recognize that a reversible adiabatic process is one where no heat is exchanged with the surroundings (Q = 0).

2. **Define Entropy**: Recall that entropy (S) is a measure of the disorder or randomness in a system. For a reversible process, the change in entropy can be expressed as:
\[ \Delta S = \frac{Q_{\text{rev}}}{T} \]
where \(Q_{\text{rev}}\) is the heat exchanged reversibly and \(T\) is the temperature.

3. **Apply the Conditions of the Process**: Since we are dealing with a reversible adiabatic process, we know that:
\[ Q = 0 \]
Therefore, substituting this into the entropy equation gives us:
\[ \Delta S = \frac{0}{T} = 0 \]

4. **Conclusion**: Since the change in entropy (\(\Delta S\)) is zero, this implies that the entropy of the system remains constant throughout the reversible adiabatic process.

### Final Answer:
The entropy of the system undergoing a reversible adiabatic process is **constant**.

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