Which of the following is the correct relationship between the number of carbon and hydrogen atoms in alkenes?

The correct option is C_nH_2n.

Step-by-Step Explanation:

1. Alkenes are a class of unsaturated hydrocarbons that contain at least one carbon-to-carbon double bond (C=C).
2. The presence of a double bond reduces the number of hydrogen atoms that can bond to the carbon skeleton compared to saturated hydrocarbons (alkanes).
3. The simplest alkene is ethene, which has the chemical formula C₂H₄. Here, the number of carbon atoms ($n$) is 2, and the number of hydrogen atoms is 4, which is equal to $2n$ (since $2\times 2=4$).
4. Similarly, propene has the chemical formula C₃H₆, where the number of carbon atoms ($n$) is 3, and the number of hydrogen atoms is 6 ($2\times 3=6$).
5. Generalizing this pattern for any acyclic alkene with one double bond, for every $n$ carbon atoms, there are always $2n$ hydrogen atoms.

Therefore, the general formula representing the relationship between the number of carbon and hydrogen atoms in alkenes is C_nH_2n.