Identify the likely transformation sequence

From the given reagents, the transformation clearly involves the standard aromatic conversion:

$\text{Benzene} \rightarrow \text{chlorobenzene} \rightarrow \text{aniline} \rightarrow \text{benzenediazonium chloride} \rightarrow \text{phenol}$

This is because:

• $Cl_2/FeCl_3$ gives chlorination of benzene.
• $Fe/HCl$ is used in reduction of a nitro group to an amine, so this suggests the intermediate before this step must be a nitro compound.
• $NaNO_2/HCl, 0^\circ C$ converts aniline to diazonium salt.
• $H_2O/H^+$ hydrolyzes diazonium salt to phenol.

Check the logical order of reactions

The only chemically meaningful sequence among the options is:

• First, electrophilic chlorination: $\text{Benzene} \xrightarrow{Cl_2/FeCl_3} \text{chlorobenzene}$

• Then (implied nitration if present in the scheme image), reduction of nitro group: $\text{chloronitrobenzene} \xrightarrow{Fe/HCl} \text{chloroaniline}$

• Diazotization: $\text{chloroaniline} \xrightarrow{NaNO_2/HCl,\ 0^\circ C} \text{chlorobenzenediazonium chloride}$

• Hydrolysis: $\text{chlorobenzenediazonium chloride} \xrightarrow{H_2O/H^+} \text{chlorophenol}$

Thus the order of the listed reagents must be:

$(i)\ Cl_2, FeCl_3 \quad (ii)\ Fe, HCl \quad (iii)\ NaNO_2, HCl, 0^\circ C \quad (iv)\ H_2O/H^+$

Evaluate options

• A: Starts with $Fe/HCl$ → impossible at the beginning unless a nitro group already exists.
• B: Starts with $Fe/HCl$ and puts chlorination at the end → incorrect order.
• C: $(i)\ Cl_2, FeCl_3 \rightarrow (ii)\ Fe,HCl \rightarrow (iii)\ NaNO_2,HCl,0^\circ C \rightarrow (iv)\ H_2O/H^+$ This is chemically consistent.
• D: Diazotization before reduction to amine → impossible.

Correct answer

$\boxed{\text{C}}$