However great the pressure, a gas cannot be liquefied above its

Options

A. Boyle temperature
B. Inversion temperature
C. Critical temperature
D. Room temperature

Answer

To solve the question "However great the pressure, a gas cannot be liquefied above its...", we need to understand the concepts of critical temperature and critical pressure in the context of gases.

### Step-by-Step Solution:

1. **Understanding the Concept of Liquefaction**:
- Liquefaction of a gas refers to the process of converting a gas into a liquid. This typically requires both pressure and a decrease in temperature.

2. **Critical Temperature Definition**:
- The critical temperature (Tc) is the maximum temperature at which a gas can be converted into a liquid, regardless of the pressure applied. Above this temperature, no amount of pressure will cause the gas to liquefy.

3. **Graphical Representation**:
- In the P-V (Pressure-Volume) graph for real gases, there is a critical point that defines the boundary between the gas phase and the liquid phase. Above the critical temperature, the gas cannot exist in the liquid phase.

4. **Implications of Critical Temperature**:
- If a gas is above its critical temperature, increasing the pressure will not lead to liquefaction. This is because the kinetic energy of the gas molecules is too high to allow them to come together and form a liquid.

5. **Conclusion**:
- Therefore, the answer to the question is that a gas cannot be liquefied above its **critical temperature**.

### Final Answer:
A gas cannot be liquefied above its **critical temperature**.