Thiosulphte ${S_2O_3}^{2-}$ is oxidized to ________ in presence of permanganate ion.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → ${SO_4}^{2-}$
Reaction:
In acidic medium, thiosulphate ion (S₂O₃²⁻) is oxidized by permanganate (MnO₄⁻) to sulphate ion (SO₄²⁻).
Balanced equation (acidic medium):
8 MnO₄⁻ + 3 S₂O₃²⁻ + H₂O → 8 MnO₂ + 6 SO₄²⁻ + 2 OH⁻ (or more commonly written with H⁺ in complete form)
Key point: Each sulfur in S₂O₃²⁻ (average oxidation state +2) is oxidized to +6 in SO₄²⁻.