Give examples and suggest reasons for the following features of the transition metal chemistry:

(i) The lower oxide have low oxidation state while the higher oxide has high oxidation state, example MnO is basic and Mn2O7 is acidic. 

(ii)  oxygen and fluorine have a small size and high electronegativity and can easily oxidize metals, example V2O5. 

(iii) oxoanions of metals have higher oxidation states because of high electronegativity of oxygen and highly oxidizing property example, Cr in CrO72- has an oxidation state of +6