Which of the following alcohols gives turbidity almost immediately at room temperature with Lucas reagent (anhydrous $\mathrm{ZnCl}{}_2$ in conc. $\mathrm{HCl}$)?

Lucas reagent converts alcohols to alkyl chlorides through carbocations, so the rate follows carbocation stability, $3^{\circ }>2^{\circ }>1^{\circ }$. Only the tertiary alcohol, 2-methylpropan-2-ol, reacts at once to give insoluble $(\mathrm{CH}{}_3){}_3\mathrm{C}-\mathrm{Cl}$ and turbidity. Butan-2-ol needs about 5 minutes and the primary alcohols do not react at room temperature.