Chemistry - Complete P-block Question with Solution | TestHub

On heating, H₃PO₂ and H₃PO₃ disproportionate to form H₃PO₄ and PH₃, where phosphorus reaches its lowest oxidation state of -3. Similarly, HClO disproportionates into HClO₃ and HCl, where chlorine reaches its lowest oxidation state of -1. Conversely, H₂SO₄ cannot undergo disproportionation because sulfur is already in its maximum oxidation state ($+6$) and cannot be oxidized further. Thus, options (A), (B), and (C) are correct.