Select correct adsorption isobars for chemisorption and physisrption respectively (where `x/m` = extent of adsorption , T = temperature )

Options

A.
B.
C.
D.

Answer

To solve the question regarding the correct adsorption isobars for chemisorption and physisorption, we will analyze the characteristics of each type of adsorption and how they relate to temperature and the extent of adsorption (x/m).

### Step-by-Step Solution:

1. **Understanding Adsorption**:
- Adsorption is the process where atoms, ions, or molecules from a gas, liquid, or dissolved solid adhere to a surface.
- The extent of adsorption is represented as \( \frac{x}{m} \), where \( x \) is the mass of the adsorbate and \( m \) is the mass of the adsorbent.

2. **Types of Adsorption**:
- **Physisorption**: This is a physical process where weak van der Waals forces are involved. The bonds formed are weak and can easily be broken.
- **Chemisorption**: This involves the formation of strong chemical bonds between the adsorbate and adsorbent. It requires higher energy and is typically irreversible.

3. **Behavior with Temperature**:
- For **Physisorption**:
- As the temperature increases, the extent of adsorption (\( \frac{x}{m} \)) decreases. This is because the increased kinetic energy allows the adsorbate molecules to overcome the weak van der Waals forces, leading to desorption.
- The graph will show a downward trend as temperature increases.

- For **Chemisorption**:
- Initially, as temperature increases, the extent of adsorption (\( \frac{x}{m} \)) increases because higher temperatures provide the necessary energy to overcome the activation energy barrier for bond formation.
- However, after reaching a certain point, the extent of adsorption will start to decrease as the bonds may begin to break due to excessive energy, leading to desorption.
- The graph will show an initial increase followed by a decrease.

4. **Conclusion**:
- The correct adsorption isobars for chemisorption will show an initial increase followed by a decrease with temperature, while physisorption will show a continuous decrease with increasing temperature.
- Therefore, the correct answer is:
- Chemisorption: Increases then decreases with temperature.
- Physisorption: Decreases with temperature.

### Final Answer:
- The correct adsorption isobars are:
- Chemisorption: Increases then decreases.
- Physisorption: Decreases.