Purple of Cassius is:

Provide information about the charge on colloidal particles.

When a gel is left standing,it loses a small amount of liquid or water. This phenomenon is called .....

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$a$. Cheese	$i$. dispersion of liquid in liquid
$b$. Pumice stone	$ii$. dispersion of liquid in gas
$c$. Hair cream	$iii$. dispersion of gas in solid
$d$. Cloud	$iv$. dispersion of liquid in solid

Choose the most appropriate answer from the options given below:

Consider the following statements about the Tyndall effect:
$(I)$ It is used to distinguish between a true solution and a colloidal solution.
$(II)$ It is possible only when the refractive indices of the dispersed phase and the dispersion medium differ significantly.
$(III)$ It is observed only when the size of the colloidal particles is much smaller than the wavelength of the light used.
Which of the following statements are correct?

Which of the following anions has the lowest coagulating power for the precipitation of a positive sol?