Which of the following compounds is antiaromatic?

Step-by-step solution

To determine whether a compound is aromatic, antiaromatic, or non-aromatic, we use Huckel's rule. A compound is antiaromatic if it is cyclic, planar, completely conjugated, and has 4n electrons (where n = 1, 2, 3, ). Let us analyze each option: Option (A): Pyrimidine is a six-membered heterocyclic ring with 3 double bonds. The lone pairs on the nitrogen atoms reside in sp^2 hybridized orbitals and do not participate in resonance. The ring has 6 electrons, which satisfies the (4n+2) electron rule for n=1 . It is aro