Aluminium chloride exists as dimer. Give reason.

Explanation

**Step-by-Step Solution:**

1. **Understanding Aluminium's Electron Configuration:**
- Aluminium (Al) has the electron configuration of 1s² 2s² 2p⁶ 3s² 3p¹. This shows that aluminium has three electrons in its outermost shell (valence shell).

2. **Valency of Aluminium:**
- The valency of aluminium is +3, as it tends to lose its three valence electrons to achieve a stable electronic configuration similar to that of noble gases.

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