Balanced chemical reaction: 3Mg + 2Fe(NO₃)₃ → 2Fe + 3Mg(NO₃)₂.
Oxidation number of iron in iron(III) nitrate is +3, oxidation number of magnesium in magnesium nitrate is +2.
The reactivity
series is
a series of metals from highest to lowest reactivity. Metal higher in the
reactivity series will displace another, magnesium is more reactive than iron.