Question

What are the oxidation numbers of S atoms in $ S_4O_6^{2-} $?

• A. 6, –1, –1.6
• B. 5, 0, 0, 5
• C. 2.5, 2.5, 2.5, 2.5
• D. 7, –2, –2, 7

Hint:

In mixed oxidation state compounds like \( S_4O_6^{2-} \), terminal S atoms bonded to O are +5; bridging S atoms are 0.

Answer 1

The Correct Option is B

The structure of \( S_4O_6^{2-} \) (tetrathionate ion) contains:
- Two terminal sulfur atoms bonded to oxygen atoms → oxidation state = +5
- Two internal sulfur atoms bonded only to other sulfur atoms → oxidation state = 0
Hence, oxidation numbers: \[ S_1 = +5,\quad S_2 = 0,\quad S_3 = 0,\quad S_4 = +5 \] Total: \[ 5 + 0 + 0 + 5 = +10;\quad \text{Oxygen total} = 6(-2) = -12;\quad \text{Overall charge} = -2 \Rightarrow +10 + (-12) = -2 \ \checkmark \]