The charge on $As_2S_3$ sol is due to the adsorbed

Critical Micelle Concentration $(CMC)$ for a soap solution is $1.5 \times 10^{-4} \ mol \ L^{-1}$. Micelle formation is possible only when the concentration of soap solution in $mol \ L^{-1}$ is:

The correct statements about the properties of colloidal solutions are:
$A$. Tyndall effect is used to distinguish between a colloidal solution and a true solution
$B$. Zeta potential is related to movement of colloidal particles
$C$. Brownian motion in colloidal solution is faster if the viscosity of the solution is very high.
$D$. Brownian motion stabilises the sols

Which of the following is not correct?

Why do we add alum to purify water?

The correct statement$(s)$ related to colloids is(are):
$(A)$ The process of precipitating colloidal sol by an electrolyte is called peptization.
$(B)$ Colloidal solution freezes at a higher temperature than the true solution at the same concentration.
$(C)$ Surfactants form micelles above the critical micelle concentration $(CMC)$. $CMC$ depends on temperature.
$(D)$ Micelles are macromolecular colloids.