Which term refers to a group of chemicals that share similar properties and can be represented by a general formula?

• A. Isomeric series
• B. Homologous series
• C. Functional group family
• D. Reaction series

Answer: (B)

Homologous series describes a group of compounds that share a common functional group and similar properties. Members differ by a repeating CH2 unit, so each step adds one methylene group and gradually changes physical properties like boiling point. This repeating unit lets the whole set be described by a single general formula that depends on n, the number of carbon atoms. For alkanes, that general formula is CnH2n+2, so increasing n gives methane, ethane, propane, and so on. This combination of a shared functional group, similar chemistry, and a general formula across the series is why the term fits best.