contestada

Which equation obeys the law of conservation of mass? H2(g) + O2(g) → H2O(g)

H2(g) + O2(g) → H2O(g) +4He(g)

2H2(g) + O2(g) → 2H2O(g)

H2(g) → H2O(g)

H2(g) + O2(g) → 2H2O(g)