Chemistry

Surface Chemistry

Question:

Which of the following substances will precipitate the negatively charged emulsions?
(a) KCl (b) Glucose
(c) Urea (d) NaCl

Answer:

(a, d) KCl and NaCl contain K+and Na+which will precipitate negatively charged emulsions.

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Surface Chemistry

Q 1.

Which of the following curves is in accordance with Freundlich adsorption isotherm?
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-11

Q 2.

Why is chemisorption referred to as activated adsorption?

Q 3.

Why does leather get hardened after tanning?

Q 4.

What is the role of desorption in the process of catalysis.

Q 5.

How does a solid catalyst enhance the rate of combination of gaseous molecules?

Q 6.

Assertion (A): Detergents with low CMC are more economical to use. Reason (R): Cleansing action of detergents involves the formation of micelles. These are formed when the concentration of detergents becomes equal to CMC.

Q 7.

What are the applications of adsorption in chemical analysis?

Q 8.

What is collodion?

Q 9.

What is the role of diffusion in heterogeneous catalysis?

Q 10.

Why is chemisorption referred to as activated adsorption?

Q 11.

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

Q 12.

What do you mean by activity and selectivity of catalysts?

Q 13.

Which of the following phenomenon occurs when a chalk stick is dipped in ink?
(a) Adsorption of coloured substance
(b) Adsorption of solvent
(c) Absorption and adsorption both of solvent
(d) Absorption of solvent.

Q 14.

What is an adsorption isotherm? Describe Freundlich adsorption isotherm.

Q 15.

Discuss the effect of pressure and temperature on the adsorption of gases on solids.

Q 16.

Which phenomenon occurs when an electric field is applied to a-colloidal solution and electrophoresis is prevented?
(a) Reverse osmosis takes place.
(b) Electroosmosis takes place.
(c) Dispersion medium begins to move.
(d) Dispersion medium becomes stationary.

Q 17.

In a reaction, catalyst changes  
(a) physically (b) qualitatively
(c) chemically (d) quantitatively

Q 18.

Why is it important to have clean surface in surface studies?

Q 19.

What causes Brownian motion in colloidal dispersion?

Q 20.

A colloid is formed by adding FeCl3  in excess of hot water. What will happen if excess sodium chloride is added to this colloid?

Q 21.

How will you distinguish between dispersed phase and dispersion medium in an emulsion?

Q 22.

Why does bleeding stop by rubbing moist alum?

Q 23.

Why do physisorption and chemisorption behave differently with rise in temperature?

Q 24.

Why does the white precipitate of silver halide become coloured in the presence of dye eosin.

Q 25.

How does a delta form at the meeting place of sea and river water?

Q 26.

Give an example where physisorption changes to chemisorption with rise in temperature. Explain the reason for change.

Q 27.

Method of formation of solution is given in Column I. Match it with the type of solution given in Column II.
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-17

Q 28.

In the following questions, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the following choices:
(a) Both Assertion and Reason are correct and the Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason arc correct but Reason is not the correct explanation for Assertion.
(c) Assertion is correct but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.
(e) Assertion is incorrect but Reason is correct

Assertion (A): An ordinary filter paper impregnated with collodion solution stops the flow of colloidal particles.
Reason (R): Pore size of the filter paper becomes more than size of colloidal particle.

Q 29.

Why are powdered substances more effective . adsorbents than their crystalline forms?

Q 30.

What modification can you suggest in the Hardy Schulze, law?

Q 31.

What is the difference between physisorption and chemisorption?

Q 32.

Give reason why a finely divided substance is more effective as an adsorbent?

Q 33.

Why is adsorption always exothermic?

Q 34.

Which of the following electrolytes will have maximum coagulating value
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-7

Q 35.

Which of the following options are correct?
(a) Micelle formation by soap in aqueous solution is possible at all temperatures.
(b) Micelle formation by soap in aqueous solution occurs above a particular concentration.
(c) On dilution of soap solution micelles may revert to individual ions.
(d) Soap solution behaves as a normal strong electrolyte at all concentrations.

Q 36.

An emulsion cannot be broken by and
(a) heating
(b) adding more amount of dispersion medium
(c) freezing
(d) adding emulsifying agent

Q 37.

Which of the following colloids cannot be coagulated easily?
(a) Lyophobic colloids (b) Irreversible colloids
(c) Reversible colloids (d) Lyophilic colloids

Q 38.

What happens when a lyophilic sol is added to a lyophobic sol?
(a) Lyophobic sol is protected.
(b) Lyophilic sol is protected.
(c) Film of lyophilic sol is formed over lyophobic sol.
(d) Film of lyophobic sol is formed over lyophilic sol.

Q 39.

What happens when gelatin is mixed with gold sol?

Q 40.

How do emulsifying agents stabilize the emulsion?

Q 41.

How does the precipitation of colloidal smoke take place in Cottrell precipitator?

Q 42.

Why is Fe(OH)3colloid positively charged, when prepared by adding FeCl3 to hot water?

Q 43.

What happens when dialysis is prolonged?

Q 44.

How does a delta form at the meeting place of sea and river water?

Q 45.

Do the vital functions of the body such as digestion get affected during fever? Explain your answer.

Q 46.

Match the items of Column I ahd Column II.
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-24

Q 47.

Assertion (A): Colloidal solutions show colligative properties.
Reason (R): Colloidal particles are large in size.

Q 48.

Assertion (A): Colloidal solutions do not show Brownian motion.
Reason (R): Brownian motion is responsible for stability of sols.

Q 49.

What is the role of adsorption in heterogeneous catalysis?

Q 50.

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