Which is used in the manufacture of plastic

Options

A. `CH_(2)=CHCl`
B. `CH-=CH`
C. `CH_(2)=CH-CH_(2)I`
D. `C Cl_(4)`

Explanation

To solve the question "Which is used in the manufacture of plastic?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Type of Plastic**:
- The question asks about a specific type of plastic. One common plastic is Polyvinyl Chloride (PVC).

2. **Determine the Monomer**:
- PVC is made from a monomer called vinyl chloride. The chemical structure of vinyl chloride is represented as CH2=CHCl, which indicates that it has a double bond between carbon atoms and a chlorine atom attached to one of the carbons.

3. **Understand the Polymerization Process**:
- Vinyl chloride undergoes a polymerization process to form polyvinyl chloride (PVC). During this process, the double bond in vinyl chloride opens up and links with other vinyl chloride molecules, creating long chains of PVC.

4. **Write the Chemical Structures**:
- The structure of vinyl chloride is:
\[ \text{CH}_2=\text{CHCl} \]
- When polymerized, it forms:
\[ \text{(CH}_2-\text{CHCl)}_n \]
- This represents the repeating unit in the polymer chain of PVC.

5. **Conclusion**:
- Therefore, the monomer used in the manufacture of PVC, which is a common plastic, is vinyl chloride (CH2=CHCl).

### Final Answer:
The monomer used in the manufacture of plastic (specifically PVC) is **vinyl chloride (CH2=CHCl)**.

---