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How many moles of KMnO4 are required to react with one mole of sulphite ion (SO3²-) in acidic solution?
- 2/5
- 3/5
- 4/5
- 1
Correct answer: 2/5
Solution
Electrons lost per SO3²-: S(+4) -> S(+6), loss = 2. Electrons gained per MnO4-: Mn(+7) -> Mn(+2), gain = 5. For 1 mol SO3²-: moles of KMnO4 = 2/5.
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