Question

Explain why particles of a colloidal solution do not settle down when left undisturbed, while in case of a suspension the do?

Answer 1

Colloidal particles are smaller in size. They remain in state of zig-zag motion (Brownian motion) always,
so the force of gravity is encountered and they do not settle down. But the particles in suspension are larger in size, so they settle down under the influence of gravity.

Answer 2

In suspensions the particle size is greater than 100 nano metre and is visible to naked eye which shows that gravity attracts it . the colloidal particles are very small that they can not be seen with the naked eye , their density is practically negligible.hence they do not settle down