The correct statements among $I$ to $III$ are:
$I$. Valence bond theory cannot explain the color exhibited by transition metal complexes.
$II$. Valence bond theory can predict quantitatively the magnetic properties of transition metal complexes.
$III$. Valence bond theory cannot distinguish ligands as weak and strong field ones.

The number of complexes from the following with no electrons in the $t_{2g}$ orbital is: $TiCl_4, [MnO_4]^{-}, [FeO_4]^{2-}, [FeCl_4]^{-}, [CoCl_4]^{2-}$

Write down the number of $3d$ electrons in each of the following ions:
$Ti^{2+}, V^{2+}, Cr^{3+}, Mn^{2+}, Fe^{2+}, Fe^{3+}, Co^{2+}, Ni^{2+}$ and $Cu^{2+}$
Indicate how you would expect the five $3d$ orbitals to be occupied for these hydrated ions (octahedral).

Which relationship is correct for the crystal field splitting energy between octahedral $(\Delta_0)$ and tetrahedral $(\Delta_t)$ complexes?

Given below are two statements: Statement $I$: Each electron in $e_g$ orbitals destabilizes the orbitals by $+0.6\Delta_o$ and each electron in the $t_{2g}$ orbitals stabilizes the orbitals by $-0.4\Delta_o$ in an octahedral field on the basis of crystal field theory. Statement $II$: All the $d$-orbitals of the transition metals have the same energy in their free atomic state but when a complex is formed the ligands destroy the degeneracy of these orbitals on the basis of crystal field theory. In the light of the above statements,choose the correct answer from the options given below:

What is the relationship between the observed colour of a coordination complex and the wavelength of light absorbed by it?