(i)
When nitrobenzene undergoes a reduction reaction, then -NO₂ group gets reduced into -NH₂ , and aniline is formed as a product.

In the next step, aniline undergoes a diazotization reaction with NaNO₂ , and HCl and benzene diazonium chloride is obtained as a product. Then benzene diazonium chloride reacts with CuCN/KCN and benzonitrile is obtained as a product. 

In the last step, hydrolysis of -CN group takes place, and benzoic acid is obtained as a product. 

The reactions is as follows:

(ii)
When benzene undergoes a nitration reaction then nitrobenzene is obtained as a product. NO₂ group is an electron-withdrawing group hence meta directing. Hence, when nitrobenzene reacts with bromine then bromination occurs in the meta position. 

In the next step, the reduction of -NO₂ group by Sn/HCl takes place and m-bromoaniline is obtained as a product. In the next step, the Aniline derivative is converted into diazonium salt by reacting with NaNO₂ and HCl at low temperatures. 

Then diazonium salt reacts with H₂SO₄ and m-bromophenol is obtained as a product.

The reactions are as follows:

(iii)

In the first reaction, benzoic acid reacts with SOCl₂ and a nucleophilic substitution reaction takes place. The -OH group from
benzoic acid is replaced by a Cl atom. In the next step, Benzoyl chloride reacts with ammonia, and an amide is formed as a product. 

Then amide undergoes a Hoffmann bromamide reaction and aniline is obtained as a product. In this reaction, amide reacts with NaOH and Br₂. 

The reactions are as follows:

(iv)
In the first step, aniline reacts with bromine water, and bromination occurs in all ortho and para positions.

In the next step, the diazotization reaction occurs when 2,4,6-tribromoaniline reacts with NaNO₂/HCl at a low temperature. 

Then benzene diazonium chloride was heated with HBF₄ and 2,4,6-tribromofluorobenzene. 

The reaction is as follows:

(v)
When benzyl chloride reacts with ethanolic NaCN then nucleophilic substitution reaction occurs and phenylethanenitrile is obtained as a product. 
In the next step, the reduction of the CN group takes place by using H₂ and Ni. 

The reaction is as follows:
 

(vi)
When chlorobenzene undergoes nitration then nitration occurs at the para or ortho position. Then in the next step reduction of -NO₂ group takes place by using  H₂ and Pd.  The reactions are as follows:
 

(vii)
In the first reaction, acetylation of -NH₂ group takes place, and acetanilide is obtained as a product. In the next step, bromination occurs at the para position. Then in the next step hydrolysis of the amide bond take place and p-bromoaniline is obtained as a product.

The reactions are as follows:

(viii)
The first reaction is an example of the Hoffmann bromamide reaction. Amide reacts with Br₂ and NaOH, and aniline is obtained as a product. In the next step, aniline reacts with NaNO₂ and HCl at low temperature, and benzene diazonium chloride is obtained as a product.

In the next step, benzene diazonium chloride reacts with H₃PO₂ , and benzene is obtained as a product. 

In the last step, benzene reacts with methyl chloride in the presence of Lewis acid, and toluene is obtained as a product. The reaction is an example of electrophilic aromatic substitution reaction.

The reactions are as follows:

(ix)
In the first reaction, aniline undergoes a diazotization reaction with NaNO₂ and HCl at low temperature and benzene diazonium chloride is obtained as a product. In the next step, benzene diazonium chloride reacts with CuCN/KCN, and benzonitrile is obtained as a product. 

Then hydrolysis of CN group takes place in the acidic medium and benzoic acid is obtained as a product. 
In the last step, the reduction of the COOH group takes place and benzyl alcohol is obtained as a product. The reagent used for this reaction is LiAlH₄ followed by water.