Which of these compounds is an alkane?

An alkane is a type of hydrocarbon that consists entirely of single bonds between carbon atoms and follows the general formula CnH2n+2. This formula indicates that for every n carbon atoms, there should be 2n+2 hydrogen atoms.

In the case of the compound C4H10, it contains 4 carbon atoms. According to the alkane formula, the expected number of hydrogen atoms would be 2(4) + 2 = 10, which matches C4H10 exactly. Therefore, this compound is classified as an alkane.

The other provided compounds do not fit the criteria for alkanes. For instance, C3H6, C2H4, and C5H8 either have fewer hydrogen atoms than the alkane formula requires or include double bonds or other structures that prevent them from being classified as saturated hydrocarbons (alkanes). Hence, they cannot be considered alkanes.