Question

Colloidal solutions of gold prepared by different methods are of different colours because of:

• A. variable valency of gold
• B. impurities produced by different methods
• C. different diameters of colloidal gold particles
• D. different concentration of gold particles

Answer 1

Answer: (C)

different diameters of colloidal gold particles

Different colors of colloidal gold is because of different sizes or different diameters of gold particle. Varying colours is due to surface plasmon resonance phenomenon in which larger particle will have darker colours and smaller particles will have brighter colours varying from yellow to gold.