Match List I with List II

List I Reaction of benzene diazonium chloride	List II Products

A-IV, B-I, C-III, D-II

The correct answer is option 3. A-IV, B-I, C-III, D-II.

List I Reaction of benzene diazonium chloride	List II Products

Let us look at each of the given reactions:

A. When benzene diazonium chloride reacts with hypophosphorous acid (\( \text{H}_3\text{PO}_2 \)), it undergoes a reduction reaction. The hypophosphorous acid reduces the diazonium group (\(-\text{N}_2^+\)) to a phenyl group (\(-\text{H}\)).

The general reaction is:

Benzene Diazonium Chloride (\(\text{C}_6\text{H}_5\text{N}_2\text{Cl}\)) is a diazonium salt where the diazonium group (\(-\text{N}_2^+\)) is attached to a benzene ring. It acts as a reducing agent. It reduces the diazonium group to a phenyl group while itself being oxidized to phosphorous acid (\(\text{H}_3\text{PO}_3\)).  The benzene diazonium chloride is reduced to benzene.

B. When benzene diazonium chloride (\(\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^-\)) reacts with potassium iodide (\(\text{KI}\)), it undergoes a reaction known as the Sandmeyer reaction, specifically for the substitution of the diazonium group with an iodine atom.

The reaction is:

It is a diazonium salt where the diazonium group (\(-\text{N}_2^+\)) is attached to a benzene ring. Potassium Iodide (\(\text{KI}\)) acts as a source of iodide ions (\(\text{I}^-\)). The diazonium group (\(-\text{N}_2^+\)) is replaced by the iodide ion (\(\text{I}^-\)) in a substitution reaction. The diazonium ion (\(\text{N}_2^+\)) is a good leaving group, and it gets replaced by the iodide ion to form iodobenzene (\(\text{C}_6\text{H}_5\text{I}\)). The by-products are potassium chloride (\(\text{KCl}\)) and nitrogen gas (\(\text{N}_2\)). This reaction is an example of a Sandmeyer reaction where the diazonium group is replaced by an iodine atom, leading to the formation of iodobenzene.

C. When benzene diazonium chloride (\(\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^-\)) reacts with water (\(\text{H}_2\text{O}\)), it undergoes hydrolysis. The reaction results in the formation of phenol and the release of nitrogen gas.

The reaction is:

Benzene Diazonium Chloride (\(\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^-\) is a diazonium salt where the diazonium group (\(-\text{N}_2^+\)) is attached to a benzene ring. Water acts as a nucleophile in this reaction. The diazonium group (\(-\text{N}_2^+\)) is hydrolyzed by water. The diazonium ion (\(\text{N}_2^+\)) is unstable in the presence of water and decomposes to form phenol, nitrogen gas, and hydrochloric acid. The reaction of benzene diazonium chloride with water leads to the formation of phenol, nitrogen gas, and hydrochloric acid. This hydrolysis reaction is a way to convert diazonium salts into phenols.

D. When benzene diazonium chloride (\(\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^-\)) reacts with aniline (\(\text{C}_6\text{H}_5\text{NH}_2\)), it undergoes a reaction known as the diazo coupling reaction. This reaction results in the formation of a azo compound, specifically phenylazoaniline (also known as aniline yellow).

The reaction is:

Benzene Diazonium Chloride (\(\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^-\)) is a diazonium salt where the diazonium group (\(-\text{N}_2^+\)) is attached to a benzene ring. Aniline is an aromatic amine with an amino group (\(-\text{NH}_2\)) attached to a benzene ring. It is a nucleophile in this reaction. The diazonium group (\(-\text{N}_2^+\)) is highly reactive and can couple with nucleophiles like the amino group in aniline. The diazonium ion (\(\text{N}_2^+\)) reacts with the amino group of aniline to form a diazo linkage (\(-\text{N}_2\text{-}\)) between the two benzene rings. This forms the azo compound phenylazoaniline and releases hydrochloric acid (\(\text{HCl}\)) as a by-product.

The reaction between benzene diazonium chloride and aniline results in the formation of an azo compound, phenylazoaniline, which is characterized by the presence of an azo group (\(-\text{N}_2\text{-}\)) linking two benzene rings. This type of reaction is widely used in dye chemistry for producing azo dyes.