Thiosulphate reacts differently with

Thiosulphate reacts differently with iodine and bromine in the reactions given

below:

2S2O32- + I2 → S4O62- + 2I–

S2O32-+ 2Br2+ 5H2O → 2SO42- + 2Br–+ 10 H+

Which of the following statements justifies the above dual behaviour of

thiosulphate?

(i) Bromine is a stronger oxidant than iodine.

(ii) Bromine is a weaker oxidant than iodine.

(iii) Thiosulphate undergoes oxidation by bromine and reduction by iodine

in these reactions.

(iv) Bromine undergoes oxidation and iodine undergoes a reduction in these

reactions.