Which best defines an alkane?

An alkane is best defined as a hydrocarbon with single covalent bonds. Alkanes are a category of saturated hydrocarbons, which means they contain only carbon and hydrogen atoms connected entirely by single bonds. This structure results in a general formula of C_nH_(2n+2), where 'n' represents the number of carbon atoms.

Because of this bonding arrangement, alkanes exhibit specific properties, such as being relatively stable and less reactive compared to hydrocarbons with double or triple bonds. They can be found in various forms, including straight-chain and branched structures, but their defining feature remains the presence of only single bonds.

The other choices highlight different types of hydrocarbons or characteristics that are not exclusive to alkanes. Hydrocarbons with double bonds are referred to as alkenes, gaseous hydrocarbons do not define a distinct class unless specified by molecular weight or structure, and ring structures are found in cycloalkanes or other compounds but are not defining traits of alkanes as a whole. Thus, the definition focusing on single covalent bonds accurately encapsulates what alkanes are.