What describes an alkane?

An alkane is defined as a saturated hydrocarbon comprised solely of single bonds between carbon atoms. This means that each carbon atom in an alkane forms four single covalent bonds with other atoms, typically with hydrogen atoms. This structure gives alkanes the general formula CₙH₂ₙ₊₂, indicating that they do not contain any multiple bonds (double or triple bonds) which are characteristic of unsaturated hydrocarbons.

In the context of the other options: compounds with double bonds (like alkenes) would be unsaturated and thus do not fit the description of an alkane. A compound containing a hydroxyl group, such as alcohols, indicates the presence of functional groups that are not typical of alkanes. Lastly, the presence of halogen atoms describes haloalkanes or alkyl halides, which also do not conform to the definition of alkanes. Therefore, the only description that aligns perfectly with the characteristics of alkanes is the one indicating they are saturated hydrocarbons with single bonds.