Question

In the reaction ${2 Na_2S_2O_3 + I_2 -> Na_2 S_4 O_6 + NaI}$ the oxidation number of sulphur is

• A. decreased
• B. increased
• C. unchanged
• D. none of these

Answer 1

Answer: (B)

increased

Answer 2

${Na_2S_2O_3 = + 2 + 2x-6 = 0 }$ or $2x = 4$ or $x = + 2$. ${Na_2S_4O_6 = + 2 + 4x - 12 = 0}$ or $4 x = 10$ or $x = \frac{10}{4}= 2.5$ Here, the O.N. of S is increased.