Only the surface atoms in an adsorbent play an active role in adsorption. These atoms possess some residual force such as van der Waals forces and chemical forces. In the process of adsorption. Weak adsorbate is substituting by strong adsorbete. Activated charcoal used in the gas mask is already exposed to the atmospheric air, so gases and water vapours in air are adsorbed on its surface. When the mask is exposed to chlorine atmosphere, the gases are displaced by chlorine. In general, easily liquefiable gases such as `CO_(2),NH_(3),Cl_(2),` and `SO_(2)` are adsorbed to a greater extent than the elemental gases, e.g., `H_(2),N_(2),O_(2),` He, etc.
In physical adsorption, the forces associated are

Options

A. Ionic
B. covalent
C. van der Waals
D. `H-bonding

Explanation

To answer the question regarding the forces associated with physical adsorption, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Physical Adsorption**:
- Physical adsorption, also known as physisorption, involves the adhesion of molecules (adsorbate) onto a surface (adsorbent) through weak interactions.

2. **Identifying the Types of Forces**:
- The forces that can be involved in adsorption include ionic bonds, covalent bonds, Van der Waals forces, and hydrogen bonding.

3. **Analyzing the Nature of Forces in Physical Adsorption**:
- In physical adsorption, the forces at play are primarily weak. The most relevant type of weak force in this context is Van der Waals forces.

4. **Conclusion**:
- Therefore, the forces associated with physical adsorption are Van der Waals forces.

### Final Answer:
The forces associated with physical adsorption are Van der Waals forces.

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