Ncert Exercises & Solutions

In the reactions given below, thiosulphate reacts differently with iodine than with bromine.

$2 S_{2} O_{3}^{2 -} + I_{2} \to S_{4} O_{6}^{2 -} + 2 I^{-}$

$S_{2} O_{3}^{2 -} + 2 {Br}_{2} + 5 H_{2} O \to 2 {SO}_{4}^{2 -} + 2 {Br}^{-} + 10 H^{+}$

Choose the statements among the following that best describe the above dual 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.