Name the three subgroups of hydrocarbons.

• A. Paraffins/alkanes, naphthenes/cycloalkanes, and aromatic compounds
• B. Paraffins/alkanes, aromatics, and alkenes
• C. Alkanes, Cycloalkanes, and Ketones
• D. Paraffins, naphthenes, and aromatics

Answer: (A)

The main idea is grouping hydrocarbons by the nature of their carbon–carbon bonds and ring structure into three basic subgroups: alkanes (paraffins), cycloalkanes (napthenes), and aromatic hydrocarbons. Alkanes are saturated chains or branched chains with only single bonds. Cycloalkanes are also saturated but form ring structures. Aromatic hydrocarbons contain one or more benzene-like rings with a conjugated pi-electron system, giving them distinct stability and reactivity. This framing shows why the three subgroups are paraffins/alkanes, napthenes/cycloalkanes, and aromatics. Other options either replace one group with alkenes (a different class based on unsaturation) or include non-hydrocarbon compounds like ketones, which aren’t hydrocarbons.