Question

Baeyer’s reagent is :

• A. Acidic potassium permanganate solution
• B. Acidic potassium dichromate solution
• C. Cold, dilute, aqueous solution of potassium permanganate
• D. Hot, concentrated solution of potassium permanganate

Answer 1

The Correct Option is C

Baeyer's reagent is a cold, dilute, alkaline solution of potassium permanganate KMnO₄.
It is a powerful oxidizing agent and is used as a test for unsaturation (presence of double or triple bonds) in organic compounds. The permanganate ion MnO₄^- is a deep purple color.
When it reacts with an unsaturated compound, the purple color disappears, and a brown precipitate of manganese dioxide MnO₂ forms. This decolorization of the permanganate solution is a positive test for unsaturation. It's important that the solution be cold and dilute; otherwise, the reaction may proceed too vigorously, and the permanganate may oxidize the organic compound further.