Among the following complexes,the one which shows zero crystal field stabilization energy $(CFSE)$ is

The octahedral complex of a metal ion $M^{3+}$ with four monodentate ligands $L_1, L_2, L_3$ and $L_4$ absorb wavelengths in the region of red,green,yellow and blue,respectively. The increasing order of ligand strength of the four ligands is:

The $d-$orbital electronic configuration of the complex among $[Co(en)_3]^{3+}$,$[CoF_6]^{3-}$,$[Mn(H_2O)_6]^{2+}$ and $[Zn(H_2O)_6]^{2+}$ that has the highest $CFSE$ is $:$

$[Fe(CN)_6]^{4-}$ and $[Fe(H_2O)_6]^{2+}$ show different colours in dilute solution because

The crystal field theory is successful in explaining which of the following?
$I.$ Ligands as point charges;
$II.$ Formation and structures of complexes.
$III.$ Colour;
$IV.$ Magnetic properties;
$V.$ Covalent character of metal-ligand bonding.

The electronic configuration of the central atom of the complex $[MnO_4]^{2-}$ is: