Which of the following reactions obeys the Law of Conservation of Atoms?

H2O → H2 + O2
CuSO4 + Zn → ZnCl2 + Cu
Zn + HCl → ZnCl2 + H2
PbCl2 + Al → AlCl3 + Pb
Zn + 2HCl → H2 + ZnCl2