The adsorption of gases on the surface of metals is called ……….

Explanation

The adsorption of gases on the surface of metals is called **physisorption** or **chemisorption**, depending on the nature of the interaction between the gas molecules and the metal surface.

1. **Understanding Adsorption**: Adsorption refers to the process where molecules from a gas or liquid phase adhere to the surface of a solid or liquid. This is different from absorption, where a substance is taken up into the bulk of another substance.

2. **Types of Adsorption**:
- **Physisorption**: This is a physical adsorption process where weak van der Waals forces are involved. It is generally reversible and occurs at low temperatures.
- **Chemisorption**: This is a chemical adsorption process where a strong chemical bond is formed between the adsorbate (gas) and the adsorbent (metal surface). It is usually irreversible and occurs at higher temperatures.

...