Concept:The reactivity of halogen acids with alcohols follows the order HI > HBr > HCl, based on bond dissociation energy and the strength of the acid.
Formula:Not applicable to this conceptual question.
Solution:- HCl is relatively unreactive with primary alcohols and explicitly requires a Lewis acid catalyst like anhydrous \(\text{ZnCl}_2\) (Lucas reagent) to weaken the C-O bond.
- HBr and HI are much stronger acids and more reactive; they can protonate and substitute the alcohol without requiring the \(\text{ZnCl}_2\) catalyst.
- Therefore, reactions B and C do not require the catalyst.
Why other options are incorrect:Option A is the only reaction that
does require the catalyst. Thus, choosing "Both B & C" is the complete and correct answer.
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