Concept:
Azo coupling reaction involves coupling of an aromatic diazonium salt with an activated aromatic ring such as phenol or aniline.
This reaction gives azo compounds containing the \(-\text{N}=\text{N}-\) linkage.
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Step 1: Recall the requirement for azo coupling.
Azo coupling occurs when:
• an aryl diazonium salt is present
• and it reacts with phenol or aniline in suitable medium
e}
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Step 2: Check the given options.
Option (B) contains benzenediazonium chloride reacting with phenol in alkaline medium.
This is the standard azo coupling reaction.
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Hence, the correct answer is:
\[
\boxed{(B)\ \text{C}_6\text{H}_5\text{N}_2\text{Cl} + \text{C}_6\text{H}_5\text{OH} \xrightarrow{\text{OH}^-} \dots}
\]