What is the prefix for a hydrocarbon chain with one carbon atom?

The prefix for a hydrocarbon chain with one carbon atom is "meth-." In organic chemistry, prefixes are used to indicate the number of carbon atoms in a hydrocarbon chain. The prefix "meth-" specifically denotes a single carbon atom and is derived from "methane," which is the simplest alkane with one carbon atom and the molecular formula C1H4.

Other prefixes such as "eth-" denotes two carbon atoms (as in ethane), "prop-" refers to three carbon atoms (as in propane), and "but-" indicates four carbon atoms (as in butane). Thus, "meth-" accurately describes a hydrocarbon containing only one carbon atom.