KCET 2026 Chemistry Solved Paper

Concept:Permanganate oxidises oxalate in acidic medium; balance electrons via half-reactions.Explanation:Write the oxidation half-reaction for oxalate:$\mathrm{C}_{2}\mathrm{O}_{4}^{2-} \rightarrow 2\mathrm{CO}_{2} + 2e^{-}$Write the reduction half-reaction for permanganate in acidic medium:$\mathrm{MnO}_{4}^{-} + 8\mathrm{H}^{+} + 5e^{-} \rightarrow \mathrm{Mn}^{2+} + 4\mathrm{H}_{2}\mathrm{O}$Equalise electrons: LCM of $2$ and $5$ is $10$.Multiply oxalate half-reaction by $5$ and permanganate half-reaction by $2$.Adding both half-reactions gives:$5\mathrm{C}_{2}\mathrm{O}_{4}^{2-} + 2\mathrm{MnO}_{4}^{-} + 16\mathrm{H}^{+} \rightarrow 2\mathrm{Mn}^{2+} + 8\mathrm{H}_{2}\mathrm{O} + 10\mathrm{CO}_{2}$Comparing with the given equation, $a = 5$ and $x = 2$.Answer: Option A: $5, 2$