Account for the following:
(i) Ethanal is more reactive towards nucleophilic addition reactions than propanone.
or `CH_(3)CHO` is more reactive than `CH_(3)COCH_(3)`.
(ii) Di-tert-butyl ketone does not give a `NaHSO_(3)` adduct but acetone does.

Explanation

Due to steric hindrance caused by the bulky tert-butyl groups, the bisulphite ion cannot easily approach the carbonyl group for addition.
(iii) Aldehyes are more reactive than ketones towards nucleophilic addition reaction.
(iv) HCHO reacts with HCN faster than `CH_(3)CHO`
(v) Benzaldehye is less reactive than acetaldehyde towards nucleophilic addition reaction.