All alcohols follow the general formula as C_nH_2n+2O.

Sublimation would be the best method because it is applicable for those organic compounds which pass directly from solid to vapour state on heating and vice versa on cooling. In these compounds naphthalene is volatile and benzoic acid is nonvolatile due to the formation of dimer via intermolecular hydrogen bonding.

S_N1 reaction is favoured by heavy groups on the carbon atom attached to halogen i.e

Benzyl > allyl > tertiary > primary > secondary > primary > alkyl halides

3^o C is more stable due to the stabilization of the charge by three methyl groups (or inductive effect). It can also be explained on the basis of hyperconjugation.