In the following sequence of reactions, B is
`C_(6)H_(6) underset(FeCl_(3))overset(Cl_(2))to A overset(Na)to B`

Options

A. chlorobenzene
B. benzyl chloride
C. diphenyl
D. chlorophenylmethane

Explanation

To solve the problem, we need to analyze the given sequence of reactions step by step.

### Step 1: Identify Compound A
1. **Starting Material**: The starting compound is benzene (C₆H₆).
2. **Reagents**: The reagents used are chlorine gas (Cl₂) and iron(III) chloride (FeCl₃).
3. **Electrophilic Aromatic Substitution**: In the presence of FeCl₃, Cl₂ generates a chloronium ion (Cl⁺), which acts as an electrophile.
4. **Reaction Mechanism**: The π electrons of the benzene ring attack the electrophilic Cl⁺, resulting in the formation of chlorobenzene (C₆H₅Cl) as compound A. The reaction can be summarized as:
\[ C_6H_6 + Cl_2 \xrightarrow{FeCl_3} C_6H_5Cl + HCl \]

### Step 2: Identify Compound B
1. **Starting Material**: The next step involves the compound A, which is chlorobenzene (C₆H₅Cl).
2. **Reagents**: The reagent used is sodium (Na).
3. **Reaction Type**: This reaction is a Wurtz reaction, where two molecules of chlorobenzene react with sodium to form biphenyl (C₁₂H₁₄).
4. **Reaction Mechanism**: The sodium reduces the chlorobenzene, leading to the coupling of two phenyl groups:
\[ 2 C_6H_5Cl + 2 Na \rightarrow C_{12}H_{10} + 2 NaCl \]
Here, biphenyl (C₁₂H₁₄) is formed as compound B.

### Final Compounds
- **Compound A**: Chlorobenzene (C₆H₅Cl)
- **Compound B**: Biphenyl (C₁₂H₁₄)

### Summary of Reactions
1. **C₆H₆ + Cl₂ (FeCl₃) → C₆H₅Cl (A)**
2. **2 C₆H₅Cl + 2 Na → C₁₂H₁₄ (B)**