The temperature above which,formation of micelles takes place is called

An example of a solid sol is

Butter is a colloid. It is formed when

Colloidal solution of gold is prepared by .............

Given below are two statements ($S-I$ and $S-II$):
$S-I$: Scattering of light by dispersed particles of a colloidal system is known as the Tyndall effect.
$S-II$: The diameter of the dispersed particles should not be much smaller than the wavelength of the light used.
Choose the most appropriate answer from the options given below.

Identify the correct option regarding surface phenomenon.