Which of the ${\mathrm{M}}^{2+}$ and ${\mathrm{M}}^{3+}$ ions of the first-row transition elements are stable in aqueous solution, which are oxidizing and which are reducing?

Explain why certain ligands such as ${\mathrm{F}}^{-}$ tend to bring out the maximum oxidation state of an element, whilst others such as $\mathrm{CO}$ and dipyridyl bring out the lowest oxidation states.

Give reasons why carbonyl and cyanide complexes of the later transition elements $\mathrm{Cr}, \mathrm{Mn}, \mathrm{Fe}, \mathrm{Co}, \mathrm{Ni}$ are more stable, more common, and more likely to exist than similar compounds of the $\mathrm{s}-$block or early transition elements.