The compound AgF2 is unstable compound. However, if formed, the compound acts as a very strong oxidising agent. Why?
What is the oxidation number of iron in Fe3O4?
Let x be the oxidation number of Fe.
Oxidation state of oxygen = -2
Thus,
3x + 4(-2) = 0
or
3x - 8 = 0
x = 8/3