Answer:
The atoms have been rearranged. To put it another way, it created a new substance.
The type of reaction that will occur with the given compounds is double-replacement where the components of one is replaced by that from another. This is,
K3PO4 + MgCl2 ----> Mg3(PO4)2 + KCl
Balancing the reactant and product sides,
2K3PO4 + 3MgCl2 ---> Mg3(PO4)2 + 6KCl
The thing that happens to the average kinetic energy of the molecules int the sample during the fist 3 minutes is :
the average kinetic energy decreases
You could see that the point start at around 190 and move down to the point f around 169
Hope this helps
Metals are the most abundant