However great the pressure , a gas cannot be liquified above its :

Options

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

Explanation

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

### Step-by-Step Solution:

1. **Understanding the Question**: The question is asking about a specific temperature related to the liquefaction of gases. It states that no matter how much pressure is applied, a gas cannot be liquefied above a certain temperature.

2. **Define Critical Temperature**: The critical temperature of a gas is defined as the temperature above which the gas cannot be liquefied, regardless of the pressure applied. This means that if the temperature of the gas is above its critical temperature, it will remain in the gaseous state even if subjected to high pressure.

3. **Connection to Liquefaction**: The process of liquefaction involves cooling a gas and applying pressure. However, if the temperature exceeds the critical temperature, increasing the pressure will not result in liquefaction. This is a fundamental principle in thermodynamics and physical chemistry.

4. **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**.

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