What are alkanes?

• A. Hydrocarbons that contain only single bonds
• B. Hydrocarbons with double bonds
• C. Hydrocarbons with triple bonds
• D. Aromatic hydrocarbons

Answer: (A)

Alkanes are hydrocarbons that contain only single bonds between carbon atoms. This means they are saturated, holding the maximum number of hydrogens for a given carbon skeleton. For unbranched chains, their formula is CnH2n+2, and each carbon is sp3 hybridized, giving a tetrahedral arrangement around carbon. Because there are no carbon–carbon double or triple bonds, alkanes are distinguished from other hydrocarbon classes: alkenes have carbon–carbon double bonds, alkynes have carbon–carbon triple bonds, and aromatic hydrocarbons include ring systems with delocalized electrons (not just plain single-bond chains). Examples include methane, ethane, propane, and butane. In typical conditions they’re relatively unreactive and mainly participate in combustion or substitution reactions.