12. Fill in the blanks to the following rules for assigning oxidation number. Write your answer on the line provided. 1.Atoms in their free state have an oxidation number of (A)

(+6) \mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}(-2)[+6(2)+(-2(7))=-2 Oxygen is assigned an oxidation number of, (c)EXCEPT when it is in a peroxide ion where it has an oxidation state of -1. (+1) \mathrm{H}_{2} \mathrm{O}(-2),(+7) \mathrm{MnO}_{4}^{-}(-2),(+1) \mathrm{H}_{2} \mathrm{O}_{2}(-1) Hydrogen in compounds or ions carries a(D)oxidation state, EXCEPT when combined with a metal cation. . Group (E)+ and 2A atoms in compounds carry oxidation numbers of +1 and +2, respectively. Halogens in binary compounds contain a -1 charge. (+1) \mathrm{HCl}(-1),(+1) \mathrm{NaI}(-1),(+3) \mathrm{BF}_{3}(-1) Given compounds that do not follow rules 1-7, usevalues to assign oxidation(+3)NF3(-1), (+1)ICI(-1)(F)+numbers. The sum of the oxidation numbers of individual atoms in a compound or a complex ion is equal to the charge of the compound or ion. (+1)LiCl(-1), (+2)CaO(-2)