From amongst the following alcohols the one that would react fastest with conc. HCl and anhydrous $$\text{ZnCl}_2$$, is

Lucas reagent is a mixture of concentrated $$\text{HCl}$$ and anhydrous $$\text{ZnCl}_2$$. It converts alcohols to alkyl chlorides via an $$\text{S}_\text{N}1$$ pathway for secondary and tertiary alcohols, and via $$\text{S}_\text{N}2$$ for primary alcohols. The rate of reaction therefore follows the stability of the carbocation that can be formed.

Order of reactivity:
tertiary alcohol > secondary alcohol > primary alcohol

Classify each option:
Option A 2-Butanol $$\rightarrow$$ secondary alcohol
Option B 2-Methylpropan-2-ol $$\rightarrow$$ tertiary alcohol
Option C 2-Methylpropanol (propan-2-ol) $$\rightarrow$$ secondary alcohol
Option D 1-Butanol $$\rightarrow$$ primary alcohol

The tertiary alcohol (Option B) forms the most stable tertiary carbocation, so it reacts almost instantaneously with Lucas reagent, producing turbidity fastest.

Therefore, the alcohol that reacts fastest with conc. $$\text{HCl}$$ and anhydrous $$\text{ZnCl}_2$$ is 2-Methylpropan-2-ol.

Option B which is: 2-Methylpropan-2-ol