What prefix is used for a hydrocarbon chain with seven carbons?

In organic chemistry, the prefixes used to denote the number of carbon atoms in a hydrocarbon chain follow a specific naming convention based on Latin or Greek numerical roots. For a hydrocarbon chain with seven carbon atoms, the correct prefix is "hept-." This prefix comes from the Greek word "hepta," meaning seven.

The other prefixes represent different numbers of carbon atoms: "hex-" is for six carbons, "pent-" is for five carbons, and "oct-" is for eight carbons. Thus, "hept-" is the appropriate choice for identifying a chain with seven carbons, aligning correctly with the established nomenclature for hydrocarbons.