Which of the following hydrocarbons is considered aromatic?

Benzene is the correct choice for an aromatic hydrocarbon due to its unique structure and stability. Aromatic hydrocarbons are characterized by having a ring structure with alternating double bonds, which leads to resonance. This resonance denotes that the electrons are delocalized over the entire ring, contributing to the compound's stability and distinctive chemical properties.

Benzene specifically consists of six carbon atoms arranged in a ring, with each carbon atom bonded to one hydrogen atom. The alternating double bonds are often depicted using circles in the structure to illustrate this delocalization of electrons, which is a key feature of aromaticity. In addition to structural criteria, benzene also satisfies Hückel's rule, which states that a compound must have a planar structure, be fully cyclic, and have a certain number of π electrons to be considered aromatic. Benzene possesses six π electrons, fitting the condition of having 4n + 2 π electrons, where n is a non-negative integer.

In comparison, hexene, butyne, and cyclobutane do not share these aromatic characteristics. Hexene and butyne are linear or acyclic hydrocarbons lacking the cyclic structure necessary for aromatics. Cyclobutane is a cyclic compound but does not have the delocalized