Zn + ? = ZnO, Mg + HCl = MgCl2 + ?, Au2O3 = Au + ?, Al + CuCl2 = Cu + ?, Fe + ? = FeCl3.

Question

Zn + ? = ZnO, Mg + HCl = MgCl2 + ?, Au2O3 = Au + ?, Al + CuCl2 = Cu + ?, Fe + ? = FeCl3.

Answer 1

2Zn+O2=2ZnO
Mg+HCl=MgCl2 + H2
2Au2O3=4Au+3O2

2AL+3CuCl2=2 ALCL3+3CU
 2Fe+3Cl2=2FeCl3