Total number of unpaired electrons present in the central metal atoms/ions of

$\left[\mathrm{Ni}(\mathrm{CO})_4\right],\left[\mathrm{NiCl}_4\right]^{2-},\left[\mathrm{PtCl}_2\left(\mathrm{NH}_3\right)_2\right],\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$ and $\left[\mathrm{Pt}(\mathrm{CN})_4\right]^{2-}$ is $\_\_\_\_$。

The crystal field splitting energy of $\left[\mathrm{Co}(\text { oxalate })_3\right]^{3-}$ complex is ' $n^{\prime}$ times that of the $\left[\mathrm{Cr}(\text { oxalate })_3\right]^{3-}$ complex. Here ' $n$ ' is $\_\_\_\_$ . (Assume $\Delta_0 \gg P$ )

Identify the metal ions among $\mathrm{Co^{2+}}$, $\mathrm{Ni^{2+}}$, $\mathrm{Fe^{2+}}$, $\mathrm{V^{3+}}$ and $\mathrm{Ti^{2+}}$ having a spin-only magnetic moment value more than 3.0 BM. The sum of unpaired electrons present in the high spin octahedral complexes formed by those metal ions is _________ .