Ca+H2— Na+O2— MgO+H2O— Ba(OH) —?+? HCe+. Fe —?+? PBo+Ae—?+?
Ca + H2 -> CaH2 4Na + O2 -> 2Na2O MgO + H2O -> Mg(OH)2 Ba(OH)2 -> BaO + H2O 2HCl + Fe -> FeCl2 + H2 3PbO + 2Al -> Al2O3 + 3Pb