Match List-I with List-II.

List-I	List-II
A	I. Gatterman Koch reaction
B	II. Etard reaction
C	III. Stephen reaction
D	IV. Rosenmund reaction

Reaction $$\mathrm{A}$$ shows the conversion of a nitrile to an aldehyde using:

$$\mathrm{SnCl_2/HCl}$$

followed by hydrolysis.

This reaction is known as the Stephen reaction.

$$\mathrm{R-CN \xrightarrow[\ H_2O\ ]{SnCl_2/HCl} R-CHO}$$

Therefore:

$$\mathrm{A \rightarrow III}$$

Reaction $$\mathrm{B}$$ shows oxidation of toluene using chromyl chloride:

$$\mathrm{CrO_2Cl_2}$$

to form benzaldehyde.

This reaction is known as the Etard reaction.

$$\mathrm{C_6H_5CH_3 \xrightarrow{CrO_2Cl_2} C_6H_5CHO}$$

Therefore:

$$\mathrm{B \rightarrow II}$$

Reaction $$\mathrm{C}$$ shows reduction of an acid chloride to an aldehyde using:

$$\mathrm{H_2/Pd-BaSO_4}$$

This reaction is known as the Rosenmund reduction.

$$\mathrm{R-COCl \xrightarrow{H_2/Pd-BaSO_4} R-CHO}$$

Therefore:

$$\mathrm{C \rightarrow IV}$$

Reaction $$\mathrm{D}$$ shows formylation of benzene using:

$$\mathrm{CO + HCl/AlCl_3}$$

This reaction is known as the Gatterman-Koch reaction.

$$\mathrm{C_6H_6 \xrightarrow{CO/HCl,\ AlCl_3} C_6H_5CHO}$$

Therefore:

$$\mathrm{D \rightarrow I}$$

Correct matching:

$$\boxed{\mathrm{A-III,\ B-II,\ C-IV,\ D-I}}$$