Which type of reaction is not shown by `C_2H_4` at all?

Options

A. Addition
B. Substitution
C. Oxidation
D. Elimination

Explanation

To determine which type of reaction is not shown by \( C_2H_4 \) (ethene), we need to analyze the characteristics of ethene and the types of reactions it can undergo.

### Step-by-Step Solution:

1. **Identify the Compound**:
- The compound in question is \( C_2H_4 \), which is known as ethene. It is an unsaturated hydrocarbon due to the presence of a double bond between the two carbon atoms.

2. **Understand Types of Reactions**:
- **Addition Reaction**: This is a reaction where atoms or groups are added to the double bond of an unsaturated hydrocarbon. Ethene can undergo addition reactions, such as hydrogenation, halogenation, and hydrohalogenation.
- **Substitution Reaction**: In this reaction, one atom or group in a molecule is replaced by another atom or group. This type of reaction is typical for saturated hydrocarbons (alkanes) rather than unsaturated ones.
- **Oxidation Reaction**: Ethene can undergo oxidation reactions, where it reacts with oxidizing agents to form alcohols or other products.
- **Elimination Reaction**: This involves the removal of atoms or groups from a molecule, often resulting in the formation of a double bond. Ethene can also undergo elimination reactions.

3. **Analyze Ethene's Reactivity**:
- Since ethene is an unsaturated hydrocarbon, it readily participates in addition, oxidation, and elimination reactions due to the presence of the double bond.
- However, it does not typically undergo substitution reactions because unsaturated hydrocarbons have a higher tendency to add new groups rather than replace existing ones.

4. **Conclusion**:
- Therefore, the type of reaction that \( C_2H_4 \) (ethene) does not show at all is the **substitution reaction**.

### Final Answer:
The type of reaction not shown by \( C_2H_4 \) is **substitution reaction**.

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