Give chemical tests to distinguish between
(i) Propanal and propanone
(ii) Benzaldehyde and acetophenone
(b) Arrange the following compounds in an increasing order of their property as indicated :
(i) Acetaldehyde, Acetone , Methyl tert-butyl ketone (reactivity towards HCN)
(ii) Benzoic acid ,3,4-Dinitrobenzoic acid , 4-Metthoxybenzoic acid (acid strength)
(iii) `CH_(3)CH_(2)CH(Br)(COOH), CH_(3)CH(Br)CH_(2)COOH, (CH_(3))_(2)CH COOH` (acid strength)

Explanation

(a) (i) Propanol and propanone : Propanal being an aldehyde reduces Tollen's reagent to Silver mirror but propanone being a ketone does not.
`CH_(3)underset("Propanal")(CH_(2)CH)O + 2 [Ag (NH_(3))_(2)]^(+) + 3OH^(-) to CH_(3)CH_(2)COCr underset ("Silver mirror")(2Ag darr + )4NH_(3)+ 2H_(2)O`
`CH_(3)COCH_(3) overset("Tollen's")underset("reagent")(to)` No Silver mirror.
(ii) Benzaldehyde and acetophenone : Acetophenone gives iodoform test with `NaOI` whereas benzaldehyde does not .
`CH_(3)underset("Acetophenone")(COC_(6)H_(5) + 3Na)OI to C_(6)H_(5)COONa + underset("yellow ppt")(CHI_(3)) + 2NaOH`
(b) (i) Acetaldehyde , Acetone , Methyl tert-butyl ketone (reactivity towards HCN)

(ii) 4-methoxybenxoic acid `lt` benzoic acid `lt` 3,4-dinitrobenzoic acid .
(iii) `CH_(3)CH_(2)underset(Br)underset(|)(C)HCOOH gt CH_(3)underset(Br)underset(|)(C)H-CH_(2)COOH gt CH_(3)-underset(CH_(3))underset(|)(C)H-COOH`