The molecule C3H6O can exhibit functional group isomerism. There are two functional groups possible for this molecular formula: aldehyde R-CHO and ketone R-CO-R . Here are the possible isomers:1. Propanal an aldehyde H3C-CH2-CHO2. Propanone a ketone H3C-CO-CH3These are the two possible isomers of C3H6O, exhibiting functional group isomerism.