Question

What is the basic idea of MOT how will you prove that neon molecules does not exist

Answer 1

The basic idea of the molecular orbital theory is that;

Molecular orbital theory predicts the distribution of electrons in a molecule, for instance, nitrogen gas. This helps predict properties such as bond order, shape, and electrical properties.

So to determine whether any molecule exist you need to determine its bond order.

Inert gases have complete octets of electrons so they have zero valencies and thus their bond order is zero hence exists only as monoatomic molecules.