CBSE Class 10 Science 2022 · Paper 31(B)/6 · Question 1

A functional group is an atom, or a group of atoms containing a heteroatom (such as oxygen, nitrogen or a halogen), that replaces hydrogen in a hydrocarbon chain and gives the compound its characteristic chemical properties, whatever the length and nature of the carbon chain. (a) Alcohol: $-\text{OH}$ (the hydroxyl group), as in ethanol, ${\text{CH}}_3{\text{CH}}_2\text{OH}$. (b) Ketone: $>\text{C}=\text{O}$ (a carbonyl group whose carbon is bonded to two carbon atoms; also written $-\text{CO}-$), as in propanone, ${\text{CH}}_3{\text{COCH}}_3$.