Thiosulphate reacts differently with iodine and bromine in the reaction given below
`2S_(2)O_(3)^(2-) to S_(4)O_(6)^(2-)+2I^(-)`
`S_(2)O_(3)^(2-)+2Br_(2)+5H_(2)Oto2SO_(4)^(2-)+2Br^(-)+10H^(+)`
Which of the following statements justifies the above dual behaviour of thiosulphate?

Options

A. Bromine is a stronger oxidant than iodine
B. Bromine is a weaker oxidant than iodine
C. Thiosulphate undergoes by bromine and reduction by iodine in these reactions
D. Bromine undergoes oxidation and iodine undergoes reduction in these reactions

Answer

a

Explanation

`2overset(+2)(S_(2))overset(-2)(O_(2)^(2-))(aq)+I_(2)^(0)(s)tooverset(2.5)(S_(4))O_(6)^(2-)(aq)+2I^(-)(aq)`
`overset(+2)(S_(2))overset(-2)(O_(3)^(2-))(aq)+2overset(0)(B)r_(2)(l)+5H_(2)O(l)to2overset(+6)(S)overset(2-)(O_(4)^(2-))(aq)+4Br^(-)(aq)+10H^(+)(aq)`
Bromine being stronger oxidising agent than `I_(2)`, oxidises S of `S_(2)O_(3)^(2-)` to `SO_(4)^(2-)` whereas `I_(2)` oxidises it only into `S_(4)O_(6)^(2-)` ion.