In the reaction `Na_2S_2O_3 + I_2 to Na_2S_4O_6 + NaI`(not balanced), which of the following is/are true?
I) `Na_2S_2O_3` is a reducing agent
II) Iodine is an oxidizing agent
III) It is an example of intermolecular redox reaction
IV) In `Na_2S_4O_6`, the average oxidation state of S is (+5/2)

Options

A. I,II,IV
B. I,II
C. I,II,III
D. I,II,III,IV

Answer

D

Explanation

`overset(+2)(S) to overset(+2.5)S , I^0 to I^(-1)` The oxidation number of sulphur increases from +2 to +2.5 thus it undergoes oxidation and acts as a reducing agent while the oxidation number of iodine decreases from 0 to-1 hence undergoes reduction and acts as an oxidizing agent.