(a) Adsorption of a gas on surface of solid is generally accompained by a

decrease in entropy, still it is a spontaneous process. Explain.

(b) Some substances can act both as colloids and crystalloids. Explain.

(c) What will be the charge on AGI colloidal particles when it is prepared

by adding small amount of ${\mathrm{AgNO}}_{3}$ solution to KI solution in water?

What is responsible for the development of this charge?