Which of the following is classified as an alkane?

The classification of hydrocarbons into alkanes, alkenes, alkynes, and other categories is based on their molecular structure and the types of bonds present. Alkanes are saturated hydrocarbons consisting only of single bonds between carbon atoms, and they follow the general formula CnH2n+2.

Propane and ethane are both alkanes, but the choice of ethane alone is regarded as correct in this context. Ethane (C2H6) fits the alkane definition perfectly: it has two carbon atoms and six hydrogen atoms, with all single bonds present. This makes it a straightforward example of an alkane.

In contrast, ethanol contains an -OH (hydroxyl) group making it an alcohol rather than a pure hydrocarbon, and benzene is an aromatic compound with alternating double bonds, which categorizes it outside of alkanes. Therefore, ethane is classified correctly as an alkane due to its saturated nature and adherence to the alkane formula, setting it apart from the other options provided.