Benzenediazonium chloride is formed when ........ is treated with .......... and hydrochloric acid at `0-5^@ C`.

Explanation

To answer the question about the formation of benzenediazonium chloride, we can break down the process step by step.

### Step-by-Step Solution:

1. **Identify the Reactants**:
We need to identify the organic compound (A) and the reagent (B) that will react with hydrochloric acid (HCl) to form benzenediazonium chloride.

2. **Recognize the Organic Compound**:
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