Assertion: A gas can be easily liquefied at any temperature below is critical temperature.
Reason: Liquification of a gas takes place when the average kinetic energy of the molecules is low.

Options

A. If both (`A`) and (`R`) are correct and (`R`) is the correct explanation of (`A`).
B. If both (`A`) and (`R`) are correct, but (`R`) is not the correct explanation of (`A`).
C. If (`A`) is correct, but (`R`) is incorrect.
D. If (`A`) is incorrect, but (`R`) is correct.

Explanation

To solve the question, we need to analyze the assertion and the reason provided:

### Step 1: Understand the Assertion
The assertion states: "A gas can be easily liquefied at any temperature below its critical temperature."

- **Explanation**: The critical temperature of a gas is the highest temperature at which it can exist as a liquid. Below this temperature, it is possible to liquefy the gas by applying pressure. This statement is correct.

### Step 2: Understand the Reason
The reason states: "Liquefaction of a gas takes place when the average kinetic energy of the molecules is low."

- **Explanation**: Liquefaction occurs when the molecules of a gas lose energy and come closer together, which typically happens at lower temperatures. When the average kinetic energy of the molecules is low, the attractive forces between them can overcome their kinetic energy, leading to liquefaction. This statement is also correct.

### Step 3: Analyze the Relationship
Now we need to determine if the reason correctly explains the assertion.

- The assertion is about the conditions under which a gas can be liquefied (i.e., below its critical temperature).
- The reason explains the mechanism behind liquefaction, which is the reduction of average kinetic energy of the molecules.

Since both statements are correct and the reason provides a valid explanation for the assertion, we conclude that:

### Final Conclusion
Both the assertion and the reason are correct, and the reason is the correct explanation for the assertion.

### Answer
The correct answer is: Both assertion and reason are correct, and the reason is the correct explanation for the assertion.

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