Which reagent is useful in the conversion of ethanenitrile to ethanal?

Benzonitrile on reduction with stannous chloride $(SnCl_2)$ in the presence of hydrochloric acid $(HCl)$ followed by acid hydrolysis forms:

What are $X$ and $Y$ in the following reactions?

The correct set of reagents which convert acetylene to but$-2-$enal are

What is $Z$ in the following reaction sequence?
$C_6H_5NH_2$ $\xrightarrow[(i) NaNO_2 + HCl / 273 \ K]{(ii) H_3PO_2 + H_2O}$ $\xrightarrow[(iii) CO, HCl, \text{anhydrous } AlCl_3/CuCl]{} Z$

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 $\xrightarrow{1. CrO_{2}Cl_{2}, 2. H_{3}O^{+}}$