Never. iron shows either +2 or +3 oxidation state but in Fe3O4 its oxidation state is seems to +4 but it is actually mixture of one moles FeO and one mole Fe2O3 , (FeO.Fe2O3 = Fe3O4).
Simply put, zero valent iron is elemental iron with "no charge", no oxidation state and unreacted with other elements.
+3 is the oxidation no of iron(III)
Hemoglobin carries oxygen in the blood, and it contains iron. Hemoglobin shots are a treatment for low iron or anemia. They're a replacement for the body's natural hemoglobin.
Iron has to be exposed to oxygen for oxidation to occur.
+2 for iron
Iron plays a critical role in the formation of hemoglobin.
methemoglobin
There are two Iron chlorides. Iron(II) chloride, in which iron is in +2 oxidation state, and Iron(III) chloride, in which iron is in +3 oxidation state.
The oxidation state of iron in two moles or atoms of elemental iron is zero. If you mean iron (II), the oxidation state is +2.
hemoglobin F
Iron sulphide is an ionic compound. The Iron is in a +2 oxidation state and the sulphur is in a -2 oxidation state.
+2 oxidation state
Iron has oxidation state of -2, in the Tetracarbonyl Ferrate ion
the valance number of iron is 3 why,becouse in the formula after iron there is 3.the question ask you what is the valency of Fe3O4....
3
Iron can exist in the body as ferrous or ferric, depending on what part of the biological process iron is in. For instance, iron in the plus two-oxidation state is "ferrous". Iron in the plus three-oxidation state is ferric.