Thiosulphate ions react differently with iodine and bromine, as shown below:
2S₂O₃²⁻ + I₂ → S₄O₆²⁻ + 2I⁻
S₂O₃²⁻ + 4Br₂ + 5H₂O → 2SO₄²⁻ + 8Br⁻ + 10H⁺
Which of the following statements correctly explains this difference in the behaviour of thiosulphate?
| 1. | Bromine is a stronger oxidant than iodine. |
| 2. | Bromine is a weaker oxidant than iodine. |
| 3. | Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reactions. |
| 4. | Bromine undergoes oxidation and iodine undergoes reduction in these reactions. |
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