If barium sulphate is precipitated in a solution containing potassium permanganate it is coloured pink ( violet) by :

When barium sulfate (BaSO₄) is precipitated in a solution containing potassium permanganate (KMnO₄), the BaSO₄ appears pink or violet due to the adsorption of permanganate ions onto its surface.

Explanation:

• Adsorption refers to the adhesion of ions or molecules onto the surface of a solid.
• In this scenario, permanganate ions (MnO₄⁻) from the solution adhere to the surface of the freshly precipitated barium sulfate particles.
• The inherent purple color of permanganate ions imparts a pink or violet hue to the BaSO₄ precipitate.

This phenomenon is a classic example of adsorption, where the surface properties of the precipitate lead to the accumulation of colored ions, altering its appearance.

Therefore, the correct answer is: b) adsorption of some of the permanganate