According to molecular orbital theory, all diatomic molecules with an even number of electrons will be diamagnetic. True or False?

It's impossible to do the diagrams on here, but the O2 molecule is the simplest example. It has two unpaired electrons which are obvious only when you approach the structure via the MO theory.

I'd Google "Oxygen molecular orbitals" or something like that if I were you.

False

Explanation:

Molecular orbital theory has emerged as another tool to explain the formation of chemical bonds, as well as valence bonding theory, hybridization. But its bases are supported by the wave functions coming from quantum mechanics, which offered all the support for this theory.

Within the theory of molecular orbitals we are presented with some terms. Among these, the term "diamagnetic molecules" refers to those that have only paired electrons and not necessarily those with an even number of electrons.