Which of the following expression for entropy change of an irreversible process ?

Options

A. `dS gt (dq)/(T)`
B. `dS = (dq)/(T)`
C. `dS lt (dq)/(T)`
D. `dS = (dU)/(T)`

Answer

To determine the expression for the entropy change of an irreversible process, we need to understand the relationship between heat transfer, temperature, and entropy.

### Step-by-Step Solution:

1. **Understanding Entropy Change**:
The change in entropy (ΔS) for any process can be expressed as:
\[ \Delta S = \int \frac{dQ}{T} \]
where \(dQ\) is the heat added to the system and \(T\) is the absolute temperature.

2. **Irreversible Process**:
For an irreversible process, the heat transfer is not reversible, and we need to consider that the system may not be in equilibrium. In such cases, the relationship between heat transfer and temperature is not straightforward.

3. **Inequality for Irreversible Processes**:
For irreversible processes, the change in entropy is always greater than the heat transfer divided by the temperature:
\[ \Delta S > \frac{dQ}{T} \]
This indicates that the entropy change for an irreversible process is greater than the quotient of heat transfer and temperature.

4. **Conclusion**:
Therefore, the correct expression for the entropy change of an irreversible process is:
\[ \Delta S > \frac{dQ}{T} \]
This means that the entropy change is positive and greater than the heat transferred divided by the temperature.

### Final Answer:
The expression for the entropy change of an irreversible process is:
\[ \Delta S > \frac{dQ}{T} \]