Chemistry - Complete P-block Question with Solution | TestHub

In Ostwald process for nitric acid, the catalyst used is Pt–Rh gauze, not Fe–Mo alloy, so (A) is incorrect. The oxidation of SO₂ to SO₃ in the contact process is exothermic, not endothermic, so (B) is incorrect. At high temperature, S₂ exists and is paramagnetic like O₂ due to two unpaired electrons in π* orbitals, so (C) is correct. Ozone at high concentration is unstable and can decompose explosively, so (D) is correct.