Question

Acidified potassium permanganate solution is decolourised by give reavtion

Answer 1

Alkenes react with potassium manganate(VII) solution in the cold. The colour change depends on whether the potassium manganate(VII) is used under acidic or alkaline conditions. If the potassium manganate(VII) solution is acidified with dilute sulphuric acid, the purple solution becomes colourless.