The compound or ion which is not aromatic in the following is

Step-by-step solution

Those compounds which are having cyclic conjugation, planar and contain 4 n + 2 π   electrons are aromatic compounds. The compounds which are having cyclic conjugation, planar and contain 4 nπ electrons are antiaromatic compounds. , , are aromatic compounds. Their π orbital system has p electrons that are delocalized all throughout the ring. Also, they have 4 n + 2 delocalized p electrons. is an antiaromatic compound. Its π orbital system has p electrons that are delocalized all throughout