which of the following adsorption isotherms represents the adsorption of a gas by a soild involvey multillayers of formation ? `(p_(s)`= saturation pressure)

Options

A.
B.
C.
D.

Answer

To solve the question regarding which adsorption isotherm represents the adsorption of a gas by a solid involving multilayers of formation, we need to analyze the characteristics of different adsorption isotherms.

### Step-by-Step Solution:

1. **Understand the Concept of Adsorption Isotherms**:
- Adsorption isotherms describe how the amount of adsorbate (gas) on the adsorbent (solid) varies with pressure at constant temperature.
- There are several types of adsorption isotherms, including Langmuir, Freundlich, and BET isotherms.

2. **Identify the Types of Adsorption**:
- **Physical Adsorption (Physisorption)**: Involves weak van der Waals forces and can lead to multilayer formation.
- **Chemical Adsorption (Chemisorption)**: Involves stronger chemical bonds and typically forms a monolayer.

3. **Recognize the Isotherm for Multilayer Adsorption**:
- The **BET (Brunauer-Emmett-Teller) isotherm** is specifically designed to describe multilayer adsorption. It accounts for the formation of multiple layers of adsorbate on the adsorbent surface.

4. **Examine the Graphical Representation**:
- In the BET isotherm, the graph typically shows an initial increase in adsorption with pressure, followed by a plateau as the surface becomes saturated. This indicates the formation of multiple layers of gas molecules on the solid surface.

5. **Conclusion**:
- Based on the above analysis, the correct answer to the question is that the **BET isotherm** represents the adsorption of a gas by a solid involving multilayers of formation.

### Final Answer:
The adsorption isotherm that represents the adsorption of a gas by a solid involving multilayers of formation is the **BET isotherm**.