Răspuns:
3. CaO +H2O =>Ca(OH)2
MgO+H2O =>Mg(OH)2
CO2+H2O => H2CO3
SO2+H2O => H2SO3
4. CaCO3 =>CaO+CO2
CO2 +2NaOH => Na2CO3 +H2O
CaO +2HCl=>CaCl2 +H2O
CaO + H2O => Ca(OH)2