Among the following complexes, the one that can exist as facial ( fac ) and meridional (mer) isomers is

Which of the following complex ions is expected to absorb visible light?

The total number of metal-metal bond present in $$\left[\mathrm{Co}_2(\mathrm{CO})_8\right]$$ is

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.