JEE Main 18 March 2021 Shift 1 Solved Paper

Functional isomers are those which have same molecular formula but different functional groups. C3H6O molecule can exists as aldehyde as well as ketone as follows
CH3−CH2−

CH=O

(Aldehyde)

and

CH3− C || O −CH3

(Ketone)

So, they are functional isomers of each other