Entropy change for an adiabatic reversible process is

Options

A. Positive
B. Zero
C. Negative
D. Constant

Answer

To determine the entropy change for an adiabatic reversible process, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Entropy Change**:
The change in entropy (\( \Delta S \)) for a reversible process is given by the formula:
\[ \Delta S = \frac{q_{\text{rev}}}{T} \]
where \( q_{\text{rev} } \) is the heat exchanged in a reversible process and \( T \) is the absolute temperature.

2. **Identify the Nature of the Process**:
In an adiabatic process, there is no heat exchange with the surroundings. This means that:
\[ q = 0 \]

3. **Substitute the Heat Exchange into the Entropy Formula**:
Since \( q = 0 \) for an adiabatic process, we can substitute this into the entropy change formula:
\[ \Delta S = \frac{0}{T} \]

4. **Calculate the Entropy Change**:
Since the numerator is zero, we find:
\[ \Delta S = 0 \]

5. **Conclusion**:
Therefore, the entropy change for an adiabatic reversible process is:
\[ \Delta S = 0 \]

### Final Answer:
The entropy change for an adiabatic reversible process is \( 0 \).

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