Sample 1Medium
What is the average oxidation number of sulphur in sodium tetrathionate, Na2S4O6?
Show the answer
The answer is B.
With Na = +1 and O = −2: 2(+1) + 4x + 6(−2) = 0, so 4x = 10 and x = +2.5. The fractional value is an average over the four sulphur atoms.
- A.
+2 is the average oxidation number of S in sodium thiosulphate, Na2S2O3.
- C.
+6 is the oxidation number of S in sulphate, which would make the compound carry a large positive charge here.
- D.
+4 is the oxidation number of S in sulphite or SO2, not in Na2S4O6.
NCERT: Class 11 Chemistry, Chapter 7, 7.3