MHTCET 26 Apr 2025 Shift 1 Paper

Concept:For a redox half-reaction, the total charge on the reactant side must equal the total charge on the product side.Explanation:Add the charges on the left-hand side (LHS) of the equation: the charge of $\mathrm{BiO}_{3}^{-}$ is $-1$, the charge from $6\mathrm{H}^{+}$ is $+6$, and the charge from $x$ electrons is $-x$.So, LHS charge $= -1 + 6 - x = 5 - x$.The right-hand side (RHS) has only $\mathrm{Bi}^{3+}$, with charge $+3$, and neutral water molecules.Set the charges equal to balance the reaction:$$5 - x = +3$$Solving for $x$: $x = 5 - 3 = 2$.Answer:The value of $x$ is $2$, which corresponds to option A.