Answer:
Mg is highly reactive as compared to that of Copper owing to its periodic position
Explanation:
MG lies in the second column of the periodic table while Cu lies in the 11th column of the periodic table from the left.
The elements in the first two columns are metallic in nature are highly reactive.
In CuCl2 solution, Mg being highly reactive replaces Cu but in MgCl2 solution, Cu being less reactive in nature do not replaces the Mg from the solution.
