MCQ practice · SSC Chemistry Board questions · Chapter 7: Chemical Reactions
What is the oxidation number of the central element in sulphuric acid?
Think it through first, then pick an option.
- a + 6
- b + 5
- c + 4
- d + 2
Answer and explanation
Correct answer: a + 6
H₂SO₄: 2(+1) + x + 4(−2) = 0, x = +6.
Why the other options are wrong
- b + 5: +5 is N in HNO₃; S in H₂SO₄ is +6.
- c + 4: +4 is S in H₂SO₃; H₂SO₄ has one more O, so +6.
- d + 2: +2 is S in Na₂S₂O₃; in H₂SO₄ it is +6.
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