1. Indicate the oxidation number of carbon and sulfur in the following compounds.

A) CO= +2

C) Na₂CO₃= +4

E) CH₄= -4

G) SO₂= +4

I) Na₂SO₄= +6

K) Na₂S₃0₃= +2

M) SCl₂= +2

O) SOCl₂= +4

2.) Indicate the oxidation number of phosphorous, iodine, nitrogen, tellurium, and silicon.

b) PO₃^3-= +3

d) P3O10^5-= +5

f) IO2^-= +3

h) NH₄^+= -3

j) NO₂^-= +3

l) NO₂^+= +5

N) TeO4^2-= +6

3.) Indicate the oxidation number of the metallic elements in the following compounds.

a) Fe₂O₃= +3

c) CoS= +2

e) K₃CoCl₆= +3

G) CrO₃= +6

I) K₂Cr₂O₇= +6

K) K₂MnO₄= +6

M) MnO₂= +4

O) Pb0₄= +8