Which of the following represents physical adsorption?

Options

A.
B.
C.
D.

Answer

To determine which option represents physical adsorption, we need to analyze the characteristics of physical adsorption and how it relates to temperature and gas adsorption.

### Step-by-Step Solution:

1. **Understanding Physical Adsorption**:
- Physical adsorption (physisorption) is a type of adsorption that occurs due to weak van der Waals forces. It is generally characterized by low heat of adsorption and is reversible.

2. **Temperature Dependence**:
- In physical adsorption, the amount of gas adsorbed is inversely proportional to temperature. This means that as the temperature increases, the amount of gas that can be adsorbed decreases.

3. **Exothermic Nature**:
- Physical adsorption is an exothermic process, meaning that it releases heat when gas molecules adhere to a surface. Therefore, an increase in temperature will lead to a decrease in the amount of gas adsorbed.

4. **Analyzing the Options**:
- We need to look at the provided options and identify which one shows a graph where the amount of gas adsorbed decreases with increasing temperature.

5. **Identifying the Correct Option**:
- Upon examining the options, we find that option D shows a graph where the amount of gas adsorbed decreases as the temperature increases, confirming that it represents physical adsorption.

### Conclusion:
- The correct answer is **option D**.