In [Fe(CN)₆]⁴⁻, the coordination entity has octahedral geometry. According to Valence Bond Theory, the metal ion uses its (n-1)d, ns, np orbitals for hybridisation to form d²sp³ hybrid orbitals. These hybridised orbitals overlap with ligand orbitals that donate electron pairs for bonding. CN⁻ is a strong field ligand that causes pairing of electrons, resulting in diamagnetic behaviour with no unpaired electrons.

In [FeF₆]³⁻, the coordination entity has octahedral geometry. The metal ion uses its ns, np, nd orbitals for hybridisation to form sp³d² hybrid orbitals. F⁻ is a weak field ligand that does not cause electron pairing, resulting in paramagnetic behaviour due to presence of unpaired electrons.

In [Co(C₂O₄)₃]³⁻, the coordination entity has octahedral geometry. The oxalate ion (C₂O₄²⁻) acts as a bidentate ligand. The metal ion undergoes d²sp³ hybridisation using inner d-orbitals. This results in diamagnetic behaviour as all electrons are paired due to the strong field nature of the ligand.

In [CoF₆]³⁻, the coordination entity has octahedral geometry. The metal ion uses sp³d² hybridisation involving outer d-orbitals. F⁻ being a weak field ligand does not cause pairing of electrons, resulting in paramagnetic behaviour with unpaired electrons.