A colloidal solution of Agl is prepared by two different methods shown below:

(i) What is the charge of AgI colloidal particles in the two test tube (A) and (B).
(ii) Give reason for the origin of change. 

(a) What is gel? Give an example.
(b) How is gold sol prepared by reduction method ?

136. The adsorption of gases on solids can be described by Frundlich’s reaction:
$\left(\frac{\mathrm{x}}{\mathrm{m}}\right)={\mathrm{kp}}^{1/4}$

(i) How are the values of k and n determined experimentally?
(ii) Explain why the value of n should be equal to or greater than one?

Explain the following observations:
(a) Ferric hydroxide sol gets coagulated on addition of sodium chloride solution.
(b) Cottrell’s smoke precipitator is fitted at the mouth of the chimney used in factories.
(c) Physical adsorption is multi layered, while chemisorption non layered.