Match Column I with Column II for the oxidation states of the central atoms .
`{:("Column I","Column II"),((i) Cr_2O_7^(2-),(a)+3),((ii) MnO_4^(-),(b)+4),((iii) VO_3^(-),(c)+5),((iv) FeF_6^(3-),(e)+7):}`

Explanation

(i) O.N of Cr in `Cr_(2)O__(7)^(21-)=+6`
(ii) O.N Of Mn `MnO_(4)^(-)=+7`
(iii) O.N of V in `O_(3)^(-)=x+3(-2)=-1 or x=+5`
(iv) O.N of F in `FeF_(6)^(3-)=x+6(-1)=-3 or x=+3` Thus correct matching is `(i) rarr(d),(ii)rarr(e ),(iii)rarr(c ),(iv)rarr(a)`