Question

In which of the following pairs of chemical species does sulfur (S) not have the same oxidation number?

• A. S₂ and H₂S
• B. H₂SO₃ and SO₂
• C. HS⁻ and S²⁻
• D. H₂S and S₂⁻

Hint:

To determine the oxidation number, balance the total charge of the molecule or ion with the known oxidation states of other atoms.

Answer 1

The Correct Option is B

The oxidation numbers of sulfur in the given species are:

1. S₂ (0) and H₂S (−2) – Different oxidation numbers.
2. H₂SO₃ (+4) and SO₂ (+4) – Same oxidation numbers.
3. HS⁻ (−1) and S²⁻ (−2) – Different oxidation numbers.
4. H₂S (−2) and S₂²⁻ (−1) – Different oxidation numbers.

Thus, sulfur does not have the same oxidation number in the pairs H₂SO₃ and SO₂, and HS⁻ and S²⁻.