1) 2Ca + O2 = 2CaO 2) Mg + H2SO4 = MgSO4 + H2 3) 2HCl + Ba(OH)2 = BaCl2 + 2H2O Ответ: 2Ca + O2 = 2CaO, Mg + H2SO4 = MgSO4 + H2, 2HCl + Ba(OH)2 = BaCl2 + 2H2O