Question

Match the items given in Column I and Column II.

Column I	Column II
(i) Protective colloid	(a) \[\ce{FeCl3 + NaOH}\]
(ii) Liquid-liquid colloid	(b) Lyophilic colloids
(iii) Positively charged colloid	(c) Emulsion
(iv) Negatively charged colloid	(d) \[\ce{FeCl3}\] + hot water

Answer 1

Column I	Column II
(i) Protective colloid	(b) Lyophilic colloids
(ii) Liquid-liquid colloid	(c) Emulsion
(iii) Positively charged colloid	(d) \[\ce{FeCl3}\] + hot water
(iv) Negatively charged colloid	(a) \[\ce{FeCl3 + NaOH}\]

Explanation:

(i) Lyophilic colloids have a unique property of protecting lyophobic colloids. When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around lyophobic particles and thus protect colloid.

(ii) If a mixture of two immiscible or partially miscible liquids is shaken, a coarse dispersion of one liquid in the other is obtained which is called emulsion. 

(iii) If \[\ce{FeCl3}\] is added to excess of hot water, a positively charged sol of hydrated ferric oxide is formed due to adsorption of \[\ce{Fe3+}\] ions. 

(iv) When ferric chloride is added to \[\ce{NaOH}\] a negatively charged sol is obtained with adsorption of \[\ce{OH-}\] ions.