WAEC Chemistry 2017 Paper

Concept:The principal functional group decides the parent name and receives the lowest locant.Explanation:The compound $\mathrm{ClCH_2CH_2OH}$ has a two-carbon chain derived from ethanol. The hydroxyl group $-\mathrm{OH}$ is the principal functional group, so the base name is ethanol. Number the chain from the carbon attached to $-\mathrm{OH}$, making that carbon C-1. The other carbon, which carries the chlorine atom, then becomes C-2. Hence, the chloro substituent is located at position 2. The correct IUPAC name is therefore 2-chloroethanol.Answer:D. 2-chloroethanol