Chemistry 5 Marks Questions

	Column I		Column II
(i)	Sulphur vapours passed through cold water.	(b)	Molecular colloids.
(ii)	Soap mixed with water above critical micelle concentration.	(c)	Associated colloid.
(iii)	White of egg whipped with water.	(d)	Macro molecular colloids.
(iv)	Soap mixed with water below critical micelle concentration.	(a)	Normal electrolyte solution.

Explanation:

1. By passing vapours of Sulphur through cold water sulphur sol can be prepared which is a molecular colloid.
2. When soap is mixed with water above critical micelle concentration forms associated colloid.
3. White of egg whipped with water forms macromolecular colloid.
4. Soap mixed with water below critical micelle concentration behave as normal electrolyte.

	Column I		Column II
(i)	Butter.	(d)	Dispersion of liquid in solid.
(ii)	Pumice stone.	(c)	Dispersion of gas in solid.
(iii)	Milk.	(a)	Dispersion of liquid in liquid.
(iv)	Paints.	(b)	Dispersion of solid in liquid.

Explanation:

1. Butter is an example of dispersion of liquid in solid.
2. Pumice stone is an example of dispersion of gas in solid in which gas bubbles are pierced within solid particles.
3. Milk is a dispersion of liquid in which fats and protein are dissolved in milk.
4. Paint is an example of solid in liquid.

	Column I		Column II
(i)	Dispersion medium moves in an electric field.	(c)	Electroosmosis.
(ii)	Solvent molecules pass through semi permeable membrane towards solvent side.	(d)	Reverse osmosis.
(iii)	Movement of charged colloidal particles under the influence of applied electric potential towards oppositely charged electrodes.	(b)	Electrophoresis.
(iv)	Solvent molecules pass through semi permeable membranes towards solution side.	(a)	Osmosis.

Explanation:

1. Dispersion medium moves in an electric field is known as electroosmosis.
2. Solvent molecules pass through semipermeable membrane towards
3. solvent side is known as reverse osmosis.
4. Movement of charged colloidal particles under the influence of applied electric potential towards oppositely charge electrodes is known as electrophoresis.
5. Solvent molecules pass through semipermeable membranes towards solution side is known as osmosis.

	Column I		Column II
(i)	Solid in liquid.	(b)	Sol.
(ii)	Liquid in solid.	(c)	Gel.
(iii)	Liquid in liquid.	(d)	Emulsion.
(iv)	Gas in liquid.	(a)	Foam.

Explanation:

Colloids are classified on the basis of types of dispersed phase and dispersion medium.

	Dispersed phase	Dispersion medium	Name
(i)	Solid	Liquid	Sol
(ii)	Liquid	Solid	Gal
(iii)	Liquid	Liquid	Emulsion
(iv)	Gas	Liquid	Foam

	Column I		Column II
(i)	Dialysis.	(d)	Purification.
(ii)	Peptisation.	(c)	Colloidal sol formation.
(iii)	Emulsification.	(a)	Cleansing action of soap.
(iv)	Electrophoresis.	(b)	Coagulation.

Explanation:

1. Dialysis: Process used for the purification of colloid.
2. Peptisation: Peptisation may be defined as the process of converting a precipitate into colloidal sol by shaking it with dispersion medium in the presence of small amount of electrolyte.
3. Emulsification: Process of cleansing of oil and dirt from soap by emulsification.
4. Electrophoresis: The movement of colloidal particles under an applied electric potential is called electrophoresis.

The role of heterogeneous catalysts can be explained in terms of adsorption of reactants on the surface of the catalyst. The adsorption helps the reaction in the following ways:

1. Adsorption increases the concentration of reactants on the surface of the catalyst. Due to increased concentration of the reactants, the reactions proceed rapidly.
2. Adsorbed molecules get dissociated to form active species like free radicals which react faster than molecules.
3. The adsorbed molecules are not free to move about and, therefore, they collide with other molecules on the surface.
4. The heat of adsorption evolved acts as energy of activation for the reaction (chemisorptions).

Example:

Adsorption of molecules of the reactant at the active site. Occurrence of chemical reaction on the surface of catalyst Desorption of product molecules.