Chemistry - Redox Reactions Question with Solution | TestHub

$\left[{\text{A}}^{\text{n}+}\to \stackrel{+5}{\text{A}}{\text{O}}_3{}^{-}+\left(5-\text{n}\right) {\text{e}}^{-}\right] \times 5,$Oxidation half reaction

$\left[{\mathrm{MnO}}_4^{-}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-}\to {\mathrm{Mn}}^{2+}+4{\mathrm{H}}_2\mathrm{O}\right] \times (5-\mathrm{n}),$Reduction half reaction

Applying reaction stoichiometry,

${\text{5 moles of A}}^{\text{n+}}= \left(\text{5-n}\right){\text{ moles of MnO}}_4^{\mathrm{-}}$
$\frac{\text{5}}{\text{5-n}}=\frac{\text{2.68}\times 10^{-3}}{\text{1.61}\times {\text{10}}^{-3}}=\text{1.66}=\frac{\text{5}}{\text{3}}$
$5-\text{n}=3$
$\therefore \text{n}=2$