What happens when a solution of benzene diazonium bromide and an aqueous solution potassium iodide are shaken together?

Iodobenzene is formed

The answer is (3). When a solution of benzene diazonium bromide and an aqueous solution of potassium iodide are shaken together, iodobenzene is formed. The reaction is as follows:

The diazonium ion \((C_6H_5N_2^+)\) reacts with the iodide ion \((I^-)\) to form iodobenzene \((C_6H_5I)\) and potassium bromide \((KBr)\). Nitrogen gas \((N_2)\) is also produced as a byproduct of the reaction.

The other options are incorrect. Bromobenzene is not formed because the bromide ion is not a strong enough nucleophile to displace the bromine atom from benzene diazonium bromide. A dihaloarene is not formed because the reaction is not a halogenation reaction. No reaction does not occur because the diazonium ion is a very reactive species and will react with any nucleophile that is available.