Reducing agents decolorize acidified KMnO4

Steps:

• Acidified potassium manganate(VII) (KMnO4) acts as an oxidizing agent, turning from purple to colorless when reduced.
• The compound must be a reducing agent capable of reducing MnO4- to Mn2+ in acidic conditions.
• Evaluate each option (1, 2, 3) based on whether they contain functional groups or structures that donate electrons.
• Options 2 and 3 qualify as they have reducible features like double bonds or alcohols, while 1 does not.

Why C is correct:

• C identifies 2 and 3 as unsaturated or oxidizable compounds that reduce Mn(VII) per the half-reaction: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O.

Why the others are wrong:

• A includes 1, which lacks reducing properties and won't decolorize KMnO4.
• B excludes 3, missing a valid reducing agent like an alkene.
• D excludes 2, ignoring another compound with oxidizable groups.

Not enough information on specific compounds 1, 2, and 3.

Final answer: C