Answer:
because Redox means two words:reduction and oxidation
reduction is when oxygen is taken from a substance while oxidation is the addition of oxygen to a substance..Magnesium displaces chlorine from iron(fe)because it is more reactive than iron
and iron gives chlorine to magnesium because it's less reactive.This is due to their position on reactivity series.
Explanation:
This is called displacement reaction where by A most reactive metal remove a substance from a less reactive metal and form up a salt
and in this case the salt formed in the reaction is 3MgCl
