What is the general formula for alkenes?

The general formula for alkenes is represented as CnH2n. This formula indicates that for every 'n' carbon atoms present in the molecule, there are '2n' hydrogen atoms. Alkenes are a class of hydrocarbons that contain at least one carbon-carbon double bond (C=C). This double bond is what characterizes alkenes and distinguishes them from alkanes, which have only single bonds and follow the formula CnH2n+2.

In the case of alkenes, the double bond allows for fewer hydrogen atoms compared to alkanes, which explains why the formula is CnH2n rather than CnH2n+2. Thus, for any given number of carbon atoms n, the corresponding number of hydrogen atoms is calculated simply by doubling n. For example, if there are 2 carbon atoms (n=2), the number of hydrogen atoms would be 2*2 = 4, resulting in the molecule ethene (C2H4).

Other formulas in the choices provided do not accurately reflect the structure of alkenes. For instance, CnH2n+2 applies to alkanes, while CnH2n-2 and C