Reaction of `Br_2` on ethylene in presence of NaCl gives

Options

A. `BrCH_2-CH_2Br`
B. `ClCH_2-CH_2Br`
C. Both (a) and (b)
D. None of these

Explanation

To solve the problem of the reaction of \( \text{Br}_2 \) on ethylene in the presence of \( \text{NaCl} \), we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are ethylene (\( \text{C}_2\text{H}_4 \)) and bromine (\( \text{Br}_2 \)). The presence of sodium chloride (\( \text{NaCl} \)) indicates that chloride ions (\( \text{Cl}^- \)) will also be involved in the reaction.

### Step 2: Understand the Mechanism
The reaction proceeds through an electrophilic addition mechanism. Ethylene, which has a double bond, acts as a nucleophile and will react with the electrophile, \( \text{Br}_2 \).

### Step 3: Electrophilic Attack
When \( \text{Br}_2 \) approaches the double bond of ethylene, it undergoes heterolytic cleavage to form a bromonium ion. This results in the formation of a carbocation intermediate:
- The double bond attacks one of the bromine atoms, forming a cyclic bromonium ion.
- The bromine atom that is not bonded to the ethylene becomes a bromide ion (\( \text{Br}^- \)).

### Step 4: Nucleophilic Attack by Chloride Ion
In the presence of \( \text{NaCl} \), the chloride ion (\( \text{Cl}^- \)) can now attack the carbocation formed from the bromonium ion. This can happen in two ways:
1. The \( \text{Br}^- \) can attack the carbocation, leading to the formation of 1,2-dibromoethane (\( \text{C}_2\text{H}_4\text{Br}_2 \)).
2. The \( \text{Cl}^- \) can attack the carbocation, leading to the formation of 1-bromo-2-chloroethane (\( \text{C}_2\text{H}_4\text{BrCl} \)).

### Step 5: Write the Products
The products of the reaction are:
1. 1,2-dibromoethane (\( \text{C}_2\text{H}_4\text{Br}_2 \))
2. 1-bromo-2-chloroethane (\( \text{C}_2\text{H}_4\text{BrCl} \))

### Conclusion
Thus, the reaction of \( \text{Br}_2 \) on ethylene in the presence of \( \text{NaCl} \) yields two products: 1,2-dibromoethane and 1-bromo-2-chloroethane.