Describe simple chemical tests that would distinguish between: (a) benzene and toluene; (b) bromobenzene and bromocyclohexane; (c) bromobenzene and 3 -bromo-1-hexene: (d) ethylbenzene and benzyl alcohol \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{OH}\right)\).

(a) Benzene and toluene can be distinguished using oxidation test with potassium permanganate (\(KMnO_4\)) in alkaline medium. Benzene shows no reaction, while toluene oxidizes to benzoic acid. (b) Bromobenzene and bromocyclohexane can be distinguished using sodium metal substitution reaction. Bromocyclohexane reacts to give a cyclohexene smell, while bromobenzene doesn't. (c) Bromobenzene and 3-bromo-1-hexene can be distinguished using Baeyer’s test with dilute alkaline potassium permanganate solution. Bromobenzene shows no reaction, whereas 3-bromo-1-hexene decolorizes the solution due to the presence of a carbon-carbon double bond. (d) Ethylbenzene and benzyl alcohol can be distinguished using Lucas test with \(ZnCl_2\) and concentrated HCl. Benzyl alcohol turns white turbid due to benzyl chloride formation, while ethylbenzene does not react.