Question

Which of the following does not fall under a single homologous series?

• A. Propene
• B. 1 - Butene
• C. 2 - Butane
• D. 2 - Butyne

Answer 1

The correct option is D

2 - Butyne

(a), (b) and (c) are alkenes: they have the same general formula $\&$ have similar chemical properties (common properties, in general that characterize the functional group). Hence they are part of the same homologous series.

(d) is an alkyne and hence is a different category of hydrocarbon.