In which thermodynamic process the temperature of the system decreases ?

Options

A. Adiabatic compression
B. Isothermal compression
C. Isothermal expansion
D. Adiabatic expansion

Answer

To determine in which thermodynamic process the temperature of the system decreases, we will analyze the different processes mentioned: adiabatic, isothermal, and their respective compressions and expansions.

### Step-by-Step Solution:

1. **Understanding Thermodynamic Processes**:
- **Isothermal Process**: In this process, the temperature of the system remains constant. Therefore, it cannot be the process in which the temperature decreases.
- **Adiabatic Process**: In this process, there is no heat exchange with the surroundings. The temperature can change depending on whether the process is compression or expansion.

2. **Analyzing Isothermal Processes**:
- **Isothermal Compression**: The temperature remains constant.
- **Isothermal Expansion**: The temperature remains constant.
- Since both isothermal processes maintain constant temperature, they do not lead to a decrease in temperature.

3. **Analyzing Adiabatic Processes**:
- **Adiabatic Compression**: In this process, the gas is compressed, and work is done on the gas, which increases its internal energy and thus raises its temperature.
- **Adiabatic Expansion**: In this process, the gas expands, and as it does work on the surroundings, it loses internal energy, which results in a decrease in temperature.

4. **Conclusion**:
- The process in which the temperature of the system decreases is **Adiabatic Expansion**.

### Final Answer:
The thermodynamic process in which the temperature of the system decreases is **Adiabatic Expansion**.

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