The structural formula of the compound which yields eth- ylene upon reaction with zinc is:

Options

A. `CH_(2)"Br"-CH_(2)` Br
B. `"CHBr_(2)-CHBr_(2)`
C. `CH_(3)CH_(2)Br`
D. none of these

Answer

To solve the question regarding the structural formula of the compound that yields ethylene upon reaction with zinc, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Desired Product**:
- We want to produce ethylene (C2H4), which is an alkene. This indicates that we need to remove two hydrogen atoms from a compound that contains a carbon-carbon bond.

2. **Identifying the Reaction Type**:
- The reaction involves the elimination of a halogen (X) from a haloalkane in the presence of zinc. This is typically a dehalogenation reaction.

3. **Choosing the Right Haloalkane**:
- A suitable haloalkane that can yield ethylene upon reaction with zinc is 1,2-dibromoethane (BrCH2-CH2Br). This compound has two bromine atoms attached to adjacent carbon atoms.

4. **Mechanism of the Reaction**:
- When 1,2-dibromoethane reacts with zinc, zinc will facilitate the removal of the bromine atoms. The reaction can be represented as follows:
- Zn + BrCH2-CH2Br → C2H4 + ZnBr2
- Here, zinc acts as a reducing agent, removing the bromine atoms and forming ethylene.

5. **Writing the Structural Formula**:
- The structural formula for 1,2-dibromoethane is:
```
Br
|
H2C - C - H
| |
Br H
```

### Final Answer:
The structural formula of the compound which yields ethylene upon reaction with zinc is **1,2-dibromoethane (BrCH2-CH2Br)**.

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