In IUPAC naming, what does the suffix "-yl" indicate?

The suffix "-yl" is used in IUPAC nomenclature to denote a substituent group that is derived from a parent hydrocarbon by removing one hydrogen atom. For example, if you take the alkane ethane (C2H6) and remove one hydrogen atom, you end up with the ethyl group (C2H5), which is a substituent derived from ethane. This naming convention is widely used to understand the structure of organic compounds and their functional groups.

In contrast, the other suffixes and terms in the options indicate different aspects of organic compounds. For instance, indicating a carbon chain with a double bond refers to alkenes, and the suffix typically used for that is "-ene." Alcohol groups are characterized by the "-ol" suffix, and carboxylic acids are indicated by the "-oic acid" suffix. Thus, the "-yl" suffix’s specific role in identifying substituents is what makes it significant in organic nomenclature.