1.
Z in the above reaction sequence is:
CH3CH2Cl→NaCNX→Ni/H2Y→Acetic anhydrideZ\text{CH}_3\text{CH}_2\text{Cl} \xrightarrow{\text{NaCN}} \text{X} \xrightarrow{\text{Ni/H}_2} \text{Y} \xrightarrow{\text{Acetic anhydride}} \text{Z}