Why physisorption is multi-molecular whereas chemisorption is unimolecular ?

Explanation

**Step-by-Step Solution:**

1. **Understanding Physisorption:**
- Physisorption refers to the physical adsorption of molecules onto a surface. The forces involved in physisorption are weak van der Waals forces.
- These weak interactions allow multiple layers of adsorbate molecules to be adsorbed onto the adsorbent surface.

2. **Multi-molecular Nature of Physisorption:**
- Because the van der Waals forces are not strong enough to hold the adsorbate molecules tightly to the surface, multiple layers can form.
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