Chemistry 12 Chapter 5 Exemplar Solutions Surface Chemistry Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

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V. Assertion and Reason Type

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

(i) Assertion and reason both are correct and the reason is correct explanation of assertion.

(ii) Assertion and reason both are correct but reason does not explain assertion.

(iii) Assertion is correct but reason is incorrect.

(iv) Both assertion and reason are incorrect.

(v) Assertion is incorrect but reason is correct.

Question 73:

Assertion: An ordinary filter paper impregnated with collodion solution stops the flow of colloidal particles.

Reason: Pore size of the filter paper becomes more than the size of colloidal particle.

Answer: (iii)

Question 74:

Assertion: Colloidal solutions show colligative properties.

Reason: Colloidal particles are large in size.

Answer: (ii)

Question 75:

Assertion: Colloidal solutions do not show brownian motion.

Reason: Brownian motion is responsible for stability of sols.

Answer: (v)

Question 76:

Assertion: Coagulation power of is more than .

Reason: Greater the valency of the flocculating ion added, greater is its power to cause precipitation (Hardy Schulze rule) .

Answer: (i)

Question 77:

Assertion: Detergents with low CMC are more economical to use.

Reason: Cleansing action of detergents involves the formation of micelles. These are formed when the concentration of detergents becomes equal to CMC.

Answer: (i)

VI. Long Answer Type

Question 78:

What is the role of adsorption in heterogenous catalysis?



• Reactants are adsorbed on the surface of the catalyst

• Occurrence of chemical reaction on the surface of catalyst

• Desorption.

Question 79:

What are the applications of adsorption in chemical analysis?



• In TLC

• Adsorption indicators.

• In qualitative analysis.

Question 80:

What is the role of adsorption in froth floatation process used especially for concentration of sulphide ores?



• Adsorption of pine oil on sulphide ore particles.

• Formation of emulsion.

• Hence ore comes out with froth.

• Explanation for shape selective catalysis.

Question 81:

What do you understand by shape selective catalysis? Why are zeolites good shape selective catalysts?



• Honey comb like structure of zeolites.

• Pores provide sites for reactants to react.

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