An eruption polluted the environment with a gas suspected to be H₂S, a poisonous gas. A residue team should spray the environment with:
A. water
B. moist SO₂
C. acidified KMnO₄ and water
D. water, acidified KMnO₄ and oxygen
Basically, one might think that the final answer to this question is SO2, but when we consider safety, one will definitely know that this is as if one is battling poison with poison, so it is not advisable to go for SO2.
Theoretically,
2 H₂S(g) + SO₂(g) → 3 S(s) + 2 H₂O(l) which is possible in a controlled environment.
However, when acidified KMnO4 reacts with H2S, it becomes reduced to a pale pink manganese ion. So, the answer is not acidified KMnO4.
H₂S + 2KMnO₄ → MnO₂ + K₂SO₄ + H₂O
Simplified reactions can occur in neutral/alkaline conditions. In acidic conditions, the reaction is even more efficient, producing soluble manganese (Mn²⁺) ions and sulfate.
Another reason why SO2 is not a viable option is the fact that the reaction can go out of control. Trust that we've all watched the movie titled Spies in Disguise, where one of the scenes states that one should not fight fire with fire. Now, you know what I'm talking about. If you fight fire with fire, we'll all get burnt, and that is why SO2 is not a viable option.
I wonder why sites like My School, Nigerian Scholar, and My Exam Point stick to SO2 when it is clear that the answer is option B based on context.
Special recognition goes to @stemsocial.