Sulphur dioxide reduces permanganate in acidic solution: MnO4^- + SO2 + H2O -> Mn^2+ + SO4^2- + H^+. In the balanced equation (smallest whole numbers) the coefficient of H^+ is

JEE Main levelSingle correct optionDifficulty 2 of 3rx102

Sulphur dioxide reduces permanganate in acidic solution: $MnO X_{4} X^{-} + SO X_{2} + H X_{2} O Mn X^{2 +} + SO X_{4} X^{2 -} + H X^{+}$ . In the balanced equation (smallest whole numbers) the coefficient of $H X^{+}$ is

Mn gains 5 electrons, S (+4 to +6) loses 2, so

MnO X_{4} X^{-}

SO X_{2}

= 2 : 5. Charge balance with 2

H X_{2} O

on the left gives

2 MnO X_{4} X^{-} + 5 SO X_{2} + 2 H X_{2} O 2 Mn X^{2 +} + 5 SO X_{4} X^{2 -} + 4 H X^{+}

, in which

H X^{+}

appears on the product side with coefficient 4.