How would you account for the increasing oxidising power in the series $VO_2^+ < Cr_2O_7^{2-} < MnO_4^-$?

(N/A) The oxidising power of these oxoanions depends on the stability of the lower oxidation states to which they are reduced.
As we move from $VO_2^+$ to $MnO_4^-$,the stability of the reduced species increases,which makes the reduction of the parent oxoanion more favorable.
Specifically,the reduction potentials increase in the order $VO_2^+ < Cr_2O_7^{2-} < MnO_4^-$,reflecting the increasing ease with which these species accept electrons.