The rate of physisorption increases with
(a)Decrease in temperature
(b)Increase in temperature
(c)Both A and B
(d)None of these

Options

A. Decrease in temperature
B. Increase in temperature
C. Both A and B
D. None of these

Explanation

To solve the question regarding the rate of physisorption, we need to understand the nature of physisorption and its relationship with temperature.

### Step-by-Step Solution:

1. **Understanding Physisorption**:
- Physisorption is a type of adsorption that occurs due to weak van der Waals forces. It is a physical process where molecules adhere to a surface without forming strong chemical bonds.

2. **Nature of Physisorption**:
- Physisorption is generally an exothermic process, meaning that it releases heat when it occurs. This is an important characteristic that will help us analyze the effect of temperature on the rate of physisorption.

3. **Le Chatelier's Principle**:
- According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in temperature, the equilibrium will shift in the direction that counteracts the change. For exothermic reactions, increasing the temperature shifts the equilibrium to favor the reactants, thus reducing the extent of the reaction.

4. **Effect of Temperature on Physisorption**:
- When the temperature increases, the kinetic energy of the molecules also increases. This can lead to a decrease in the rate of physisorption because the molecules have more energy to overcome the weak van der Waals forces holding them to the surface.
- Conversely, decreasing the temperature lowers the kinetic energy of the molecules, making it easier for them to adhere to the surface, thus increasing the rate of physisorption.

5. **Conclusion**:
- Based on the above analysis, we conclude that the rate of physisorption increases with a decrease in temperature. Therefore, the correct answer to the question is:
- **(a) Decrease in temperature**.

### Final Answer:
(a) Decrease in temperature