Answer:
Step-by-step explanation:
Here, we want to give a reason for why one of the reactions might not occur
Generally, a metal that is above another in the electrochemical series will displace it from its salt
Now, Aluminum is higher than copper, thus, it would displace it (from CuCl2, a reaction will occur). However, Aluminum is lower than magnesium. Thus, it will not displace it from its salt (MgCl2 and no reaction will occur)