(a) How will you convert
(i) Benzene to acetophenone
(ii) Propanone to 2-Methylpropan-2-ol
(b) Give reasons :
(i) Electrophilic substitution in benzoic acid takes place at meta position.
(ii) Carboxlic acids are higher boiling liquids than aldehydes,, ketones and alchols of comparable molecular masses.
(iii) Propanal is more reactive than propanone in nucleophilic addition reactions.

Explanation

(a) (i) Benzene to Acetophenone

(ii) Propanone to 2-Methylpropan-2-ol

(b) (i) Benzoic acid is meta directing group. It withdraws electrons density from benzene at ortho and para position made meta position comparatively electron rich.

(ii) Carboxylic acids are higher boiling liquids than aldehydes, ketones and alcohols of comparable molecular masses because of following reasons.
(a) Stronger inter-molecular H-Bonds.
(b) As compared to alcohols the O-H bond in carboxylic acids is more strongly polarised due to adjacent electron-withdrawing carbonyl group.
(c ) Due to the formation of cyclic dimers.

(iii) Propanal is more reactive than propanone in nucleophillic addition reaction because in propanone 2-alkyl i.e., electron donating groups are attached whereas in propanal one electron donating alkyl group, is attached , Greater the alkyl group lesser will be the positive charge on the carbon of carbonyl group, less reactive in nulceophillic addition reaction.