KCET 2026 Chemistry Solved Paper

Concept:Glycerol is a trihydric alcohol, so it contains three hydroxyl ($-\mathrm{OH}$) groups attached to a three-carbon chain.Explanation:The structural formula of glycerol is:$$\mathrm{CH}_{2}\mathrm{OH}-\mathrm{CHOH}-\mathrm{CH}_{2}\mathrm{OH}$$A primary alcoholic group is attached to a carbon atom bonded to only one other carbon atom.A secondary alcoholic group is attached to a carbon atom bonded to two other carbon atoms.Now examine each carbon atom bearing an $-\mathrm{OH}$ group.The two end carbon atoms belong to $\mathrm{CH}_{2}\mathrm{OH}$ groups.Each end carbon is attached to only one other carbon atom.Hence, both end groups are primary alcoholic groups.The middle carbon atom belongs to the $\mathrm{CHOH}$ group.This carbon is attached to two other carbon atoms.Hence, the middle group is a secondary alcoholic group.Therefore, glycerol contains two primary and one secondary alcoholic groups.Answer:Option B: Two primary and one secondary alcoholic groups.