Please explain the eg t2g electron filling sequence. URGENT

The five degenerate d orbitals split into two sets in presence of ligands.The eg set with two orbitals having higher energy and t2g set with 3 orbitals having lower energy.
The gap between the energies of these two sets is known as crystal field splitting energy.
The expenditure of energy required for pairing of electrons in the same region is known as pairing energy.
When the crystal field energy is less than pairing energy, all the d orbitals are singly occupied. Afterwards, the additional electrons then pair up with the electrons in t2g level first.
If the crystal field energy is more than the pairing energy, the electrons pair up in t2g level before going to eg level.
 
Example: 1) filling of electrons in weak crystal field of F- ligand

2) Filling of electrons in strong crystal field of CN- ligand

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