Answer:
Magnesium
Zinc
Iron
Copper
Explanation:
The given elements are:
Magnesium, copper, iron and zinc
We are to put them in the order from the least reactive to the most reactive of all.
To solve this problem, we simply use the activity series of metals to arrange the elements.
The activity series arranges metals from the most reactive to the least reactive. The more reactive metals displaces the lesser one from solutions.
So;
Magnesium
Zinc
Iron
Copper