MHTCET 18 Apr 2026 Shift 2 Paper

Concept:A substance shows reducing property when it itself gets oxidised (loses electrons) while reducing another species.Explanation:Analyse the oxidation-state changes in each option.In A: $\mathrm{NO} + \mathrm{O_3} \to \mathrm{NO_2} + \mathrm{O_2}$. Nitrogen changes from $+2$ to $+4$, hence $\mathrm{NO}$ is oxidised; $\mathrm{O_3}$ is reduced, so it acts as an oxidising agent.In B: $2\mathrm{KI} + \mathrm{H_2O} + \mathrm{O_3} \to 2\mathrm{KOH} + \mathrm{I_2} + \mathrm{O_2}$. Iodine changes from $-1$ to $0$, so iodide is oxidised; again $\mathrm{O_3}$ is the oxidising agent.In D: $\mathrm{PbS} + 4\mathrm{O_3} \to \mathrm{PbSO_4} + 4\mathrm{O_2}$. Sulphur changes from $-2$ to $+6$, so $\mathrm{PbS}$ is oxidised; $\mathrm{O_3}$ is the oxidising agent.In C: $\mathrm{H_2O_2} + \mathrm{O_3} \to \mathrm{H_2O} + 2\mathrm{O_2}$. Oxygen in $\mathrm{H_2O_2}$ goes from $-1$ to $0$ in $\mathrm{O_2}$, so it is oxidised; oxygen in $\mathrm{O_3}$ goes from $0$ to $-2$ in water, so it is reduced. Thus $\mathrm{O_3}$ is again the oxidising agent, not a reducing agent.Therefore, all four reactions show the oxidising property of ozone, and none show its reducing property.Answer:None of the given reactions exhibits the reducing property of ozone.