Silver iodide is used for producing artificial rain because $AgI$

Among the following methods:
$(i)$ Addition of an electrolyte
$(ii)$ Electrophoresis
$(iii)$ Addition of a protective colloid
$(iv)$ Addition of an oppositely charged sol
the coagulation of a lyophobic sol can be carried out by:

The conditions given below are in the context of observing Tyndall effect in colloidal solutions:
$A$. The diameter of the colloidal particles is comparable to the wavelength of light used.
$B$. The diameter of the colloidal particles is much smaller than the wavelength of light used.
$C$. The diameter of the colloidal particles is much larger than the wavelength of light used.
$D$. The refractive indices of the dispersed phase and the dispersion medium are comparable.
$E$. The dispersed phase has a very different refractive index from the dispersion medium.
Choose the most appropriate conditions from the options given below:

Colloidal solutions of metals like gold,silver and platinum are generally prepared by using

Brownian motion arises due to ....

How are the colloidal solutions classified on the basis of physical states of the dispersed phase and dispersion medium?