Write the reaction equation: S- SO2- H2SO3- Na2SO3- H2SO3- K2SO3

1) S + O2 = SO2 (when sulfur interacts with oxygen, sulfur dioxide is formed);

2) SO2 + H2O = H2SO3 (when sulfur dioxide interacts with water, sulfurous acid is formed);

3) H2SO3 + 2NaOH = Na2SO3 + 2H2O (when sulfurous acid reacts with sodium hydroxide, sodium sulfite and water are formed);

4) Na2SO3 + 2HCl = NaCl + H2SO3 (when sodium sulfite interacts with hydrochloric acid, sodium chloride and sulfurous acid are formed);

5) H2SO3 + 2KOH = K2SO3 + 2H2O (when sulfurous acid interacts with potassium hydroxide, potassium sulfite and water are formed).