Benzene is the only compound that is aromatic. Aromaticity refers to a special type of stability in organic molecules that contain a ring of atoms with alternating double bonds. This creates a "delocalized" system of electrons that is spread out over the entire ring, making it particularly stable and resistant to chemical reactions.
Benzene has a six-carbon ring with alternating double bonds, making it an aromatic compound. In contrast, cyclobutane, cyclopentane, hexane, and ethene do not have this type of ring and are not considered aromatic. They have different types of bonds and molecular structures that make them less stable and more reactive compared to benzene.