what is the chemical reaction equation for : Hydrogen sulfite reacts with oxygen to form sulfur dioxide and water vapour.

Answer 1

Are you sure you don't mean hydrogen sulfiDe (H2S) ? Hydrogen sulfiTe would be sulfurous acid (H2SO3), which can decompose directly into H2O and SO2.

For the oxidation of H2S,

2 H2S + 3 O2 -> 2 SO2 + 2 H2O

Answer 2

2H2S(g)+3O2(g)→2SO2(g)+2H2O(g)