Among the following,the number of reaction$(s)$ that produce$(s)$ benzaldehyde is

The reagents used in the Etard reaction $(I)$ and the Stephen reaction $(II)$ are:

Write the structures of products of the following reactions:
$(i)$ Benzene + $C_{2}H_{5}COCl$ $\xrightarrow{\text{Anhyd. } AlCl_{3}, CS_{2}}$
$(ii)$ $(C_{6}H_{5}CH_{2})_{2}Cd + 2 CH_{3}COCl \rightarrow$
$(iii)$ $H_{3}C - C \equiv C - H$ $\xrightarrow{Hg^{2+}, H_{2}SO_{4}}$
$(iv)$ $p$-Nitrotoluene $\xrightarrow{1. CrO_{2}Cl_{2}, 2. H_{3}O^{+}}$

Which,if any,of the following pairs of reagents could be used to prepare $2$-phenyl-$2$-butanol?

Explain the method of preparation of aldehydes and ketones from nitrile compounds.