Which atomic orbital contributor corresponds to the HOMO of a molecule with four π electrons in a conjugated system?

Question

Quizplus · Accepted Answer

For a molecule with four π electrons in a conjugated system, the HOMO will be the highest energy π orbital. In this case, it will be the π orbital that is half-filled (i.e., contains two electrons) and has the highest energy. Looking at the options, only option II shows a π orbital with two lobes and the same energy level as the other π orbitals in the conjugated system. Therefore, option II corresponds to the HOMO.

Which Atomic Orbital Contributor Corresponds to the HOMO of a Molecule