The formation of 1-2 dibromoethane from ethene and bromine is an example of ___________ .

Options

A. Substitution
B. Dehydration
C. Dehydrohalogenation
D. Addition

Explanation

To determine the type of reaction that occurs when ethene reacts with bromine to form 1,2-dibromoethane, we can analyze the nature of the reaction step by step.

### Step-by-Step Solution:

1. **Identify the Reactants and Products**:
- The reactants are ethene (C2H4) and bromine (Br2).
- The product is 1,2-dibromoethane (C2H4Br2).

2. **Understand the Structure of Ethene**:
- Ethene has a double bond between the two carbon atoms (C=C).
- This double bond is reactive and can undergo various types of chemical reactions.

3. **Analyze the Reaction Type**:
- **Substitution Reaction**: Involves replacing one functional group with another. This does not apply here as no functional group is being replaced.
- **Dehydration Reaction**: Involves the removal of a water molecule. This does not apply as there is no water produced or removed in this reaction.
- **Dehydrohalogenation Reaction**: Involves the elimination of hydrogen and a halogen atom. This does not apply as we are not removing any atoms; instead, we are adding bromine.
- **Addition Reaction**: Involves adding atoms or groups to a molecule. Here, bromine is added to the double bond of ethene, resulting in the formation of 1,2-dibromoethane.

4. **Conclusion**:
- Since bromine is added to the ethene molecule, breaking the double bond and forming single bonds with each carbon atom, this reaction is classified as an **addition reaction**.

### Final Answer:
The formation of 1,2-dibromoethane from ethene and bromine is an example of **addition reaction**.