Oxidatoin numbers

What is the oxidation number of N in NH₄⁺¹

• +3

• -3

• 0

• -1

What is the oxidation number of N of HNO₂

• +3

• -3

• +1

• -1

What is the oxidation number of Fe⁺³

• +3

• -3

• +2

• 0

What is the oxidation number of Mn in MnO₂

• +2

• -2

• +4

• -4

What is the oxidation number of Cr in CrO₄^-2

• +2

• +4

• +6

• +8

What is the oxidation number of Cr in Na₂Cr₂O₇

• +1

• +2

• +6

• +12