Identify the correct statements from the following:
$(i)$ $A$ closed vessel containing $90 \%$ $CO_2$ and $10 \%$ $O_2$ is an aerosol.
$(ii)$ Milk is an emulsion.
$(iii)$ Smoke is an aerosol.
$(iv)$ Peptisation is a method of purification of colloidal solution.
$(v)$ Ultrafiltration is a method of purification of colloidal solution.

Which one of the following is not a property of hydrophilic sols?

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

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:

The charge on colloidal particles can be determined by $......$.

$100 \, cm^3$ of gold sol requires $10^{-4} \, g$ of gelatin to prevent coagulation when $1 \, cm^3$ of $10 \% \, NaCl$ solution is added. The gold number of gelatin is ............ .