What are vicinal dihalides? Give an example.

Explanation

### Step-by-Step Solution:

1. **Definition of Vicinal Dihalides**:
Vicinal dihalides are organic compounds that contain two halogen atoms (such as chlorine, bromine, etc.) attached to adjacent carbon atoms in a carbon chain.

2. **Formation of Vicinal Dihalides**:
These compounds can be synthesized through the reaction of alkenes with halogens. For example, when ethene (C₂H₄) reacts with chlorine gas (Cl₂), a vicinal dihalide is formed.

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