MCQ practice · SSC Chemistry Board questions · Chapter 7: Chemical Reactions
What is the oxidation number of S in sodium thiosulphate?
Think it through first, then pick an option.
- a + 6
- b + 4
- c + 2
- d + 3
Answer and explanation
Correct answer: c + 2
2(+1) + 2x + 3(−2) = 0, so 2x = 4 and x = +2.
Why the other options are wrong
- a + 6: +6 is S in a sulphate; in thiosulphate it is +2.
- b + 4: Forgetting there are two S gives +4; 2x = 4, so x = +2.
- d + 3: 2x = 4, not 6; x = +2.
More board questions on this topic
- What is the oxidation number of sulphur in oleum?
- The compound B in the stem-
- What is the oxidation number of hydrogen in CaH₂?
- What is the oxidation number of hydrogen in LiAlH₄?
Your account is open, so all 30,000+ MCQs from every chapter are yours. Start practising SSC Chemistry →
Want to keep going?
A free account carries you on to the next questions and opens 30,000+ MCQs from every chapter. Join before launch and Chirkut bundles are 60% off.
The ones you missed, worth one more look