In the following question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Extent of physisorption of a gas increases with decrease in temperature.
Reason (R): It is due to decrease in strength of van der Waals forces.

Options

A. Both A and Rare true and R is the correct explanation of A
B. Both A and R are true but explanation of A
C. A is true but R is false
D. A is false and R is True

Explanation

To solve the question regarding the Assertion (A) and Reason (R), we will analyze both statements step by step.

### Step 1: Analyze the Assertion (A)
**Assertion (A):** Extent of physisorption of a gas increases with decrease in temperature.

- Physisorption is a type of adsorption that occurs due to weak van der Waals forces.
- It is an exothermic process, meaning that heat is released when the gas molecules adhere to the surface.
- According to Le Chatelier's principle, if the temperature decreases, the equilibrium shifts to favor the exothermic process, which in this case is physisorption.
- Therefore, as the temperature decreases, the extent of physisorption indeed increases.

**Conclusion for Assertion (A):** True.

### Step 2: Analyze the Reason (R)
**Reason (R):** It is due to decrease in strength of van der Waals forces.

- The statement suggests that the increase in physisorption with a decrease in temperature is because the strength of van der Waals forces decreases.
- However, this is incorrect. The strength of van der Waals forces does not decrease with temperature; rather, the forces remain constant.
- The reason for the increased extent of physisorption at lower temperatures is due to the exothermic nature of the process, not a decrease in the strength of the forces.

**Conclusion for Reason (R):** False.

### Final Conclusion
- Assertion (A) is true, while Reason (R) is false. Therefore, the correct choice is that the Assertion is true, but the Reason is false.

### Summary of the Answer
- Assertion (A) is true.
- Reason (R) is false.
- The answer is option 3.