What is a requirement for a compound to be classified as an alkane?

For a compound to be classified as an alkane, it must contain only single bonds between carbon atoms. Alkanes are a specific class of hydrocarbons that follow the general formula CnH2n+2, where "n" represents the number of carbon atoms. This formula indicates that each carbon atom is bonded to the maximum number of hydrogen atoms possible, resulting in a saturated hydrocarbon.

In alkanes, the presence of only single bonds means that there are no double or triple bonds, which differentiates them from alkenes and alkynes, respectively. Double bonds (as found in alkenes) or triple bonds (as found in alkynes) would result in a different classification of the compound, as these types of bonds indicate unsaturation. Furthermore, functional groups, as mentioned in one of the options, would also indicate that the compound is not simply an alkane, but rather an alcohol, ether, or another class of organic compounds, which inherently possess specific reactivity characteristics that alkanes do not. Therefore, the essential characteristic of alkanes rests solely in their structure of saturated carbon atoms connected by single bonds.