The SI unit of entropy is

Options

A. joule/kelvin
B. newton-meter
C. calorie/second
D. joule/calorie

Explanation

To determine the SI unit of entropy, we need to understand the definition and formula associated with entropy.

### Step-by-Step Solution:

1. **Understanding Entropy**:
- Entropy is a measure of the disorder or randomness in a system. It is also associated with the amount of energy in a physical system that is not available to do work.

2. **Formula for Entropy**:
- The change in entropy (ΔS) can be expressed as:
\[ \Delta S = \frac{dQ}{T} \]
where \(dQ\) is the heat added to the system and \(T\) is the absolute temperature in Kelvin.

3. **Identifying Units**:
- In the formula, \(dQ\) represents energy, which is measured in Joules (J).
- The temperature \(T\) is measured in Kelvin (K).

4. **Deriving the SI Unit**:
- From the formula, we can see that the unit of entropy (S) can be derived as:
\[ \text{Unit of Entropy} = \frac{\text{Unit of Energy}}{\text{Unit of Temperature}} = \frac{\text{Joules}}{\text{Kelvin}} = \text{Joule per Kelvin (J/K)} \]

5. **Conclusion**:
- Therefore, the SI unit of entropy is Joule per Kelvin (J/K).

### Final Answer:
The SI unit of entropy is **Joule per Kelvin (J/K)**.

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