What root corresponds to a hydrocarbon chain consisting of four carbon atoms?

The root that corresponds to a hydrocarbon chain consisting of four carbon atoms is "but-." In organic chemistry, hydrocarbons are categorized by their carbon chain length, and specific prefixes denote the number of carbon atoms present in the molecule.

For aliphatic hydrocarbons:

• "Meth-" refers to one carbon atom.
• "Eth-" refers to two carbon atoms.
• "Prop-" refers to three carbon atoms.
• "But-" represents four carbon atoms.
• "Pent-" denotes five carbon atoms.
• "Hex-" corresponds to six carbon atoms.

Given that the question asks for a hydrocarbon chain with four carbon atoms, "but-" is the appropriate root to use. The understanding of these prefixes is essential in naming compounds systematically according to IUPAC rules, which categorize organic molecules based on their structure and composition. This systematic naming helps chemists communicate unambiguously about different compounds and their structures.