$$ \text { Observe the following complex ions } $$

$$ \begin{array}{cccc} \hline\left[\mathrm{Mn}(\mathrm{CN})_6\right]^{3-} & {\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{3-}} & {\left[\mathrm{CoF}_6\right]^{3-}} & {\left[\mathrm{Co}\left(\mathrm{C}_2 \mathrm{O}_4\right)_3\right]^{3-}} \\ \hline A & B & C & D \\ \hline \end{array} $$

Identify the option in which the unpaired electrons in the complex ions are in correct increasing order

Which one of the following complex ions is diamagnetic in nature?

Total number of geometrical isomers possible for the complexes $\left[\mathrm{NiCl}_4\right]^{2-}$, $\left[\mathrm{CoCl}_2\left(\mathrm{NH}_3\right)_4\right]^{+}$, $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3\left(\mathrm{NO}_2\right)_3\right]$ and $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right]^{2+}$ is

Arrange the following complexes in the increasing order of their spin only magnetic moment (in B.M)

I. $\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}$

II. $\left[\mathrm{MnCl}_4\right]^{2-}$

III. $\left[\mathrm{Mn}(\mathrm{CN})_6\right]^{4-}$

IV. $\left.\left[\mathrm{Cr}(\mathrm{NH})_3\right)_6\right]^{3+}$