(a) Account for the following :
(i) Propanal is more reactive than propanone towards nucleophilic reagents.
(ii) Electrophilic substitution in benzoic acid takes place at meta position.
(iii) Carboxylic acids do not give characteristic reactions of carbonyl group.
(b) Give simple chemical test to distinguish between the following pairs of
compounds :
(i) Acetophenone and benzaldehyde
(ii) Benzoic acid and ethylbenzoate

1- due to increased e- density by +I effect of two ch3 group propanone becomes less reactive towards nucleophilic add. 2 = because benzoic acid shows -R effect which draws e- from o-p position so electrophile attack at meta position. 3= because nucleophile attack removes the -OH or any characteristic group from the carbon .B (1) = Iodoform test acetophenone have coch3 group gives +ve test but not given by benzaldehyde. B(2) = first hydrolyse the ethylbenzoate into benzoic acid and ethanol then Iodoform is given by ethanol as benzoic acid is same for both.