(a) (i) Write the disproportionation reaction of H₃PO₃.
(ii) Draw the structure of XeF₄.
(b) Account for the following:
(i) Although Fluorine has less negative electron gain enthalpy yet F₂ is strong oxidizing agent.
(ii) Acidic character decreases from N₂O₃ to Bi₂O₃ in group 15.
(c) Write a chemical reaction to test sulphur dioxide gas. Write chemical equation involved.