(i) Ethyl benzene when treated with $\mathrm{KMnO}_4$ and $\mathrm{KOH}$, undergoes oxidation to produce potassium benzoate. The potassium benzoate when treated with an acid forms benzoic acid. (ii) Cyclohexanol is oxidized by $\mathrm{CrO}_3$ to cyclohexanone. Cyclohexanone when treated with semicarbazide produces cyclohexanone semicarbazone.