Assertion (A): Finest gold is red in colour, as the size of the particles increases, it appears purp

Question

Assertion (A): Finest gold is red in colour, as the size of the particles increases, it appears purple then blue and finally gold. 
Reason (R): The colour of the colloidal solution depends on the wavelength of light scattered by the dispersed particles.

Professor PC Thomas Classes · Answer

The colour of a colloid depends on the wavelength of scattered light, which in turn strongly depends on the size of the colloidal particles.