Answers Assignment No – 2
Surface Chemistry
ASSERTION REASON TYPE:
Ans 1. b

Ans 2. c

Ans 3. c

Ans 4. a

Ans 5. a

ONE - WORD ANSWER
Ans 6. Coagulation

Ans 7. Electrified sand

SHORT ANSWER QUESTIONS
Ans 8. (i) Scattering of light by the colloidal particles takes place and the path of light becomes visible. This is known as Tyndall effect.
(i)              On passing an electric current, colloidal particles move towards the oppositely charged electrodes where they loose their charge and get coagulated. This process is called electrophoresis.

Ans 9. (i) The phenomenon involving the migration(movement) of colloidal particles under the influence of electric field towards the oppositely charged electrode
(i)              The process of conversion of sol into precipitate, usually done by addition of suitable electrolytes. If the coagulated particles float on the surface of dispersion medium, the coagulation is known as flocculation.

Ans 10. Micelles are produced by the aggregation of a large number of ions in concentrated sol. Aggregated particles are known as micelles also known as associated colloids.eg: soap, synthetic detergents.


Ans 11. (i) Blood is +vely charged colloid. One molecule of ferric chloride produces 3 –ve chloride ions while one molecule of potassium chloride produces one –ve chloride ion. Greater the –ve charge, faster the coagulation.  
(ii) After the reaction is over between the adsorbed reactants, the process of desorption must take place to remove the product molecules and create space for other reactant molecules to adsorb on the catalyst surface