1)NaCl+K=KCl+Na 2Na+H2O=2NaOH+H2 NaOH+H2SO4=NaHSO4=H2O NaHSO4+NaOH=Na2SO4+H2O Na2SO4+BaCl2=2NaCl+BaSO4 2)MgCl2+Ca=CaCl2+Mg 2Mg+O2=2MgO MgO+H2SO4=MgSO4+H2o MgSO4+2KOH=K2SO4+Mg(OH)2 Mg(OH)2+2HNO3=Mg(NO3)2+2H2O