Atomic number of $$\mathrm{Mn}, \mathrm{Fe}$$ and $$\mathrm{Co}$$ are 25, 26 and 27 respectively. Which of the following inner orbital octahedral complex ions are diamagnetic?

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

II. $$\left[\mathrm{Mn}(\mathrm{CN})_6\right]^{3-}$$

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

IV. $$\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{3-}$$

Choose the correct option.

Which type of isomerism is exhibited by $$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right]^{+}$$?

Specify the coordination number of cobalt in $$\left[\mathrm{Co}(\mathrm{CN})\left(\mathrm{H}_2 \mathrm{O}\right)(\mathrm{e n})^2\right]^{2+}$$

Which of the following complexes is square planar and diamagnetic?