Which class of hydrocarbons contains a triple bond?

• A. Alkanes
• B. Cycloalkanes
• C. Alkynes
• D. Aromatics

Answer: (C)

The class that contains a carbon–carbon triple bond is alkynes. A triple bond consists of one sigma and two pi bonds, which gives the carbon atoms involved sp hybridization and a linear shape. Alkynes are the hydrocarbons that routinely feature this C≡C bond, with examples like ethyne (acetylene) and propyne. They also follow the general formula for acyclic alkynes as CnH2n−2, and their names end with the -yne suffix to reflect the triple bond.

In contrast, alkanes have only single bonds and are saturated, cycloalkanes are ring structures with single bonds, and aromatics are cyclic compounds with delocalized electrons and alternating single/double bonds rather than a true triple bond. This is why alkynes are the correct class for containing a triple bond.