The structure of cyclobutadienyl dianion, C₄H₄²⁻, is shown below. It can be described by the following energy diagrams of its π molecular orbitals when only the π bonds and not the σ bonds are taken into account: 

Assign the proper numbers of π electrons to the various molecular orbitals to complete the MO energy diagram. Use up/down arrows to indicate the electrons.

The energy-level diagram for atomic and molecular orbitals in NO is given below.

If the same model is followed, count the number of MOs involved for the IBr molecule. Note: use only the valence atomic orbitals of I atom and Br atom.

Determine the valence atomic orbitals of I and Cl involved in the construction of the MOs for ICl, an interhalogen compound, assuming it has molecular orbitals similar to the homonuclear diatomic molecule of F₂

Identify NO⁺ ion as being diamagnetic or paramagnetic.