Correct Answer - C
When alcohols react with HX it is the `R-OH` bond which breaks. The more stable the carbocation formed, more is the reactivity of the alcohols. The carbocations formed in case of these alcohols (I, II, III and IV) are
`F -CH_(2)-underset((I))(overset(+)(CH))- CH_(3)`
`underset((II)) (F-CH_(2)-CH_(2)-overset(+)(CH)-CH_(3))`
`underset((III))(CH_(3)-overset(+)(CH)-CH_(3))`
`underset((IV))(C_(6)H_(5)-overset(+)(CH_(2))`
The relative stabilities of carbocations and hence the order of reactivity of corresponding alcohols is `IV gt III gt II gt I`. The greater stability of carbocation (IV) is due to resonance.
Carbocation II is a `2^(@)` carbocation and as such is quite stable. The lesser stability of carbocation I and II is due to the `-I` effect of F. Electron with-drawing effect of F is more in case of carbocation I as in this case F is nearer to the carbon carrying +ve charge.
