In balancing reactions, the number of atoms on each side should be of equal number. It is the most important rule in reactions. Also, we should know the correct substances involved in the reaction. We do as follows:
2K + MgBr2 = 2KBr + Mg
Answer: There are 20 protons neutrons in the atom
Heat; rather, or change of the molecules to make them move faster
Brass is an alloy, or a combination of two (or more) metals.