A and B are the compounds with the molecular formula C₃H₉N. These are oxidised by KMnO₄ and subjected to hydrolysis. If A gives propanal and B gives propanone, A and B are respectively

Primary amines  in which -NH₂ group is present on terminal carbon on oxidation with KMnO₄, followed by hydrolysis forms aldehydes.

A = CH₃CH₂CH₂NH₂

primary amines in which -NH₂ group is not present on terminal carbon on oxidation with KMnO₄, followed by hydrolysis forms ketones.

B = CH₃CH(NH₂)CH₃