What is the general formula for alkenes?

The general formula for alkenes is represented as CnH2n. Alkenes are hydrocarbons that contain at least one carbon-carbon double bond (C=C). The formula reflects the relationship between the number of carbon atoms (n) and the number of hydrogen atoms in the molecule due to the presence of this double bond.

In alkenes, for every carbon atom added to the chain, you can have two hydrogen atoms. However, because of the double bond, the total number of hydrogen atoms is reduced by two compared to alkanes, which have the general formula CnH2n+2. This is essential for understanding how alkenes differ from other classes of hydrocarbons, such as alkanes (which are saturated) and alkynes (which have triple bonds).

The incorrect options illustrate different types of molecular formulas but do not accurately represent alkenes: CnH2n+2 corresponds to alkanes, CnH2n-2 would suggest a formula relating to alkynes or other unsaturated forms without sufficient hydrogen, and CnH2nO hints at containing oxygen, indicating some kind of alcohol or ether, which is not relevant to the classification of alkenes.