Identify the product of the given reaction. 

Chlorobenzene

The correct answer is option 2. Chlorobenzene.

When benzene diazonium chloride (\(\text{C}_6\text{H}_5\text{N}_2\text{Cl}\)) reacts with cuprous chloride \((CuCl)\) in the presence of hydrochloric acid \((HCl)\), the reaction is known as the Sandmeyer reaction. This reaction is used to replace the diazonium group with a chlorine atom, resulting in the formation of chlorobenzene. The reaction proceeds as follows:

Here is what happens in this reaction:

Benzene diazonium chloride (\(\text{C}_6\text{H}_5\text{N}_2\text{Cl}\)) reacts with cuprous chloride \((CuCl)\). The diazonium group (\(\text{N}_2^+\)) is replaced by a chlorine atom, resulting in the formation of chlorobenzene (\(\text{C}_6\text{H}_5\text{Cl}\)). Nitrogen gas (\(\text{N}_2\)) is liberated as a by-product. Cuprous chloride \((CuCl)\) is oxidized to cupric chloride (\(\text{CuCl}_2\)).

Conclusion: The reaction of benzene diazonium chloride with \(CuCl\) produces chlorobenzene, nitrogen gas, and cupric chloride. This reaction is an example of the Sandmeyer reaction, which is commonly used to introduce halogens into aromatic compounds.