MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

Lucas reagent is a mixture of concentrated HCl and anhydrous ZnCl _2. The reaction of alcohols with Lucas reagent proceeds via an S_N1 mechanism, which involves the formation of a carbocation intermediate. The rate of reaction depends on the stability of the carbocation formed. The order of stability of carbocations is tertiary > secondary > primary. Therefore, the reactivity of alcohols towards Lucas reagent follows the order: tertiary > secondary > primary. Tertiary alcohols react instantly to form an insoluble alkyl halide, producing immediate turbidity. Secondary alcohols react in about 5 minutes to produce turbidity. Primary alcohols do not produce turbidity at room temperature. Among the given options, tert-butyl alcohol is a tertiary alcohol, so it forms a stable tertiary carbocation and reacts instantly to give turbidity. n-butyl alcohol and iso-butyl alcohol are primary alcohols, while sec-butyl alcohol is a secondary alcohol. Answer: tert - Butyl alcohol