Complexes with $CN^{-}$ ligands are generally .......

Low spin complex of $d^6$ cation in an octahedral field will have the following energy:
($\Delta_o =$ crystal field splitting energy in an octahedral field,$P =$ Electron pairing energy)

For which of the following pairs of complexes is the crystal field splitting energy $\Delta_0$ for $II > \Delta_0$ for $I$?

$I$	$II$
$(a). [Cr(H_2O)_6]^{2+}$	$[Cr(H_2O)_6]^{3+}$
$(b). [Fe(H_2O)_6]^{3+}$	$[Fe(CN)_6]^{3-}$
$(c). [Fe(CN)_6]^{3-}$	$[Ru(CN)_6]^{3-}$
$(d). [NiF_6]^{4-}$	$[NiF_6]^{2-}$

Which of the following ligands causes the maximum splitting of $d$-orbitals?

The correct order of energies of $d-$ orbitals of a metal ion in a square planar complex is:

For the crystal field splitting in octahedral complexes,