`underset("Propanal")(H-underset(H)underset(|)overset(H)overset(|)(C)-underset(H)underset(|)overset(H)overset(|)(C)-overset(O)overset(||)(C)-H" "underset("Propanone")(H-underset(H)underset(|)overset(H)overset(|)(C)-overset(O)overset(||)(C)-underset(H)underset(|)overset(H)overset(|)(C)-H)`
These two compounds are related to each other as functional isomers.