The size of a colloidal particle is:

Colloidal gold solutions prepared by different methods have different colors due to:

Action of soap is due to emulsification and micelle formation. Comment.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Finest gold is red in colour,as the size of the particles increases,it appears purple then blue and finally gold.
Assertion $R$: The colour of the colloidal solution depends on the wavelength of light scattered by the dispersed particles.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which one of the following is a hydrophilic colloidal sol?

Select the incorrect statement: