Which of the following is the correct general formula for alkenes?

The correct general formula for alkenes, which are hydrocarbons containing at least one carbon-carbon double bond, is indeed represented by the formula CnH2n. This formula indicates that for every n number of carbon atoms, there are 2n hydrogen atoms.

Alkenes have this specific formula because they are unsaturated compounds; the presence of a double bond reduces the number of hydrogen atoms that can attach to the carbon framework compared to alkanes, which follow the formula CnH2n+2. Thus, alkenes can accommodate fewer hydrogen atoms than alkanes, leading to their formula being CnH2n.

This also helps distinguish alkenes from other types of hydrocarbons like alkynes, which have a triple bond and follow a different formula (CnH2n-2), and that signifies even more unsaturation. Understanding these distinctions is crucial for accurately determining the structure and behavior of organic compounds.