Match Column I with Column II for the oxidation states of the central atoms.
Option (i) Cr2O72-→ (d) +6
By oxidation rule we can calculate the unknown oxidation number.
Cr2O72-
Option (ii) MnO-4→ (e) +7
MnO-4
Option (iii) VO-3→ (c) +5
VO-3
Option (iv) FeF3-6→ (a) +3
FeF3-6