How would you account for the following:

Cobalt(II) is stable in aqueous solution but in the presence of complexing reagents, it is easily oxidized.

Compare the chemistry of actinoids with that of the lanthanoids with special reference to:

(i) electronic configuration (iii) oxidation state

(ii) atomic and ionic sizes and (iv) chemical reactivity.

How would you account for the following:

Of the d4 species, Cr²⁺ is strongly reducing while manganese (III) is strongly oxidizing.

How would you account for the following:

The d¹ configuration is very unstable in ions.

What is meant by ‘disproportionation’? Give two examples of disproportionation reaction in aqueous solution.