Explain the cleansing action of soaps.

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

To resist the coagulation of $100 \ cc$ gold sol,$1 \ cc$ of $10 \% \ NaCl$ is added to it in the presence of $10^{-4} \ g$ gelatin. The gold number of gelatin is:

Fog is an example of a colloidal system.

The Tyndall effect is observed only when the following conditions are satisfied $:$
$1$. The diameter of the dispersed particles is much smaller than the wavelength of the light used.
$2$. The diameter of the dispersed particle is not much smaller than the wavelength of the light used.
$3$. The refractive indices of the dispersed phase and dispersion medium are almost similar in magnitude.
$4$. The refractive indices of the dispersed phase and dispersion medium differ greatly in magnitude.

$A$ $10^{-3} \ M$ solution of detergent $(C_{12}H_{25}SO_4^-Na^+)$ forms a colloidal sol. In $1 \ mm^3$ of the solution,there are on average $10^{13}$ colloidal particles. How many ions are present in one colloidal particle (micelle)? $(N_A = 6 \times 10^{23})$