В) Na2O--->NaOH--->NaHSO4--->Na2SO4-->SO3
Na2O+H2O=2NaOH
NaOH+H2SO4-->NaHSO4+H2O
NaHSO4+NaOH-->Na2SO4+H2O
Na2SO4--->Na2O+SO3
г) CaCO3-->CaO-->Ca(OH)2-->Ca(HCO3)2-->CO2
CaCO3-->CaO+CO2
CaO+H2O=Ca(OH)2
Ca(OH)2+H2CO3-->Ca(HCO3)2+H2O
Ca(HCO3)2--->2CO2+CaO+H2O