Rate of physical adsorption increases with:

Options

A. Decrease in temperature
B. Decrease in pressure
C. Increase in temperature
D. Decrease surface area

Explanation

To solve the question "Rate of physical adsorption increases with:", we will analyze each option provided and determine which one leads to an increase in the rate of physical adsorption.

### Step-by-Step Solution:

1. **Understanding Physical Adsorption**:
- Physical adsorption occurs due to weak intermolecular forces, primarily Van der Waals forces. The strength of these forces is influenced by temperature and pressure.

2. **Analyzing Each Option**:
- **Option A: Decrease in Temperature**:
- When the temperature decreases, the kinetic energy of the molecules also decreases. This allows Van der Waals forces to become more effective, leading to an increase in physical adsorption. Therefore, this option is likely correct.

- **Option B: Decrease in Pressure**:
- Physical adsorption generally increases with an increase in pressure. If the pressure decreases, the number of gas molecules available for adsorption on the surface decreases, leading to a decrease in the rate of adsorption. Hence, this option is incorrect.

- **Option C: Increase in Temperature**:
- Increasing the temperature provides more kinetic energy to the molecules, which can break the weak Van der Waals forces. This would lead to a decrease in physical adsorption. Therefore, this option is also incorrect.

- **Option D: Decrease in Surface Area**:
- A decrease in surface area means there is less area available for adsorption. This would lead to a decrease in the rate of physical adsorption. Therefore, this option is incorrect.

3. **Conclusion**:
- After analyzing all the options, we find that the rate of physical adsorption increases with a decrease in temperature. Thus, the correct answer is **Option A: Decrease in Temperature**.

### Final Answer:
The rate of physical adsorption increases with a **decrease in temperature**.

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