Chemistry · Preparation, properties and uses of K2Cr2O7 and KMnO4

Which of the following reagents is used to test the presence of gas?

Which of the following reagents is used to test the presence of \( S O_{2} \) gas?

  • A. Acidified potassium manganate
  • B. Alkaline potassium manganate
  • C. Alkaline potassium dichromate
  • D. Acidified potassium dichromate

Step-by-step solution

SO2 is a reducing agent. Acidified potassium manganate (KMnO4) is purple and gets reduced to colorless Mn2+ by SO2, providing a clear visual test. Other reagents may also react but are not standard for testing SO2.
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