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

None Do. These are all skeleton equations that must first be balances by adding coeffecients.

Also, CuSO4 + Zn - > ZnCl2 + Cu has different products in terms of elements than its reactants ...

Zn + 2HCl → H2 + ZnCl2 obeys the Law of Conservation of Atoms.

On each side of the arrow there are 1 Zn atom, 2 H atoms, and 2 Cl atoms.

Thus, all atoms are conserved.