Given example and suggest reasons for the following features of the transition metal :
The highest oxidation state is exhibited in oxoanions of a metal.

Explanation

Transition metals exhibit highest oxidation states in oxoanions. Thus Cr and Mn exhibit oxidation states of + 6 and + 7 in `overset((VI))(CrO_(4)^(2-))` and `overset((VII))(MnO_(4)^(-))`, respectively.
This is due to the small size and high electronegativity of oxygen besides its ability to form multiple bonds with the metal.