The major product $Z$ formed in the following sequence of reactions is: \ce{C2H6 ->[Cl2/UV] X ->[NH3] Y ->[(i) NaNO2/HCl][(ii) H2O] Z}

Solution & Explanation

\textbf{Answer:} (C) A primary aliphatic amine reacts with nitrous acid to give an unstable diazonium salt that instantly loses \ce{N2} and is converted to the alcohol. \textbf{Solution:} Free-radical monochlorination of ethane gives chloroethane: \ce{C2H6 ->[Cl2/UV] C2H5Cl} ($X$). Reaction with ammonia (ammonolysis) gives the primary amine ethylamine: \ce{C2H5Cl ->[NH3] C2H5NH2} ($Y$). Treatment with nitrous acid (\ce{NaNO2/HCl}) diazotises the primary aliphatic amine, but unlike aromatic diazonium salts the aliphatic diazonium ion \ce{C2H5N2+} has no ring resonance to stabilise it and decomposes instantly, evolving \ce{N2}; with water present it yields the alcohol: \ce{C2H5NH2 ->[NaNO2/HCl][H2O] C2H5OH + N2 ^}. Thus $Z$ is ethanol (C). The nitro compound (A), the diazoate (B) and the unreacted amine (D) are not the major products.