Among the following $Cr(III)$ complexes,which one will have the highest octahedral crystal field splitting?

$A$ transition metal $(M)$ among $Mn, Cr, Co$ and $Fe$ has the highest standard electrode potential $(M^{3+} / M^{2+})$. It forms a metal complex of the type $[M(CN)_6]^{4-}$. The number of electrons present in the $e_g$ orbital of the complex is $.........$

The correct increasing order for the wavelengths of absorption in the visible region for the complexes of $Co^{3+}$ is:

The homoleptic and octahedral complex of $Co^{2+}$ and $H_2O$ has $.......$ unpaired electron$(s)$ in the $t_{2g}$ set of orbitals.

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

Arrange the following in increasing order of their crystal field splitting energy:
$I. [Co(H_2O)_6]^{3+}$
$II. [Co(NH_3)_6]^{3+}$
$III. [Co(CN)_6]^{3-}$
$IV. [CoF_6]^{3-}$