MHTCET 11 Apr 2026 Shift 2 Paper

Concept:The oxidation number of an element in a polyatomic ion is calculated by setting the sum of all oxidation numbers equal to the ion's total charge.Explanation:In $\mathrm{ClO}_{4}^{-}$, let the oxidation number of chlorine be $x$.Oxygen has an oxidation number of $-2$ in most compounds.There are 4 oxygen atoms, so their total oxidation number is:$$4 \times (-2) = -8$$The overall charge on $\mathrm{ClO}_{4}^{-}$ is $-1$.Therefore, the sum of oxidation numbers is:$$x + (-8) = -1$$Simplifying:$$x - 8 = -1$$$$x = +7$$Hence, the oxidation number of Cl in $\mathrm{ClO}_{4}^{-}$ is $+7$.Answer:Option B: $+7$