Chemistry

Surface Chemistry

Question:

At the equilibrium position in the process of adsorption
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-1

Answer:

ncert-exemplar-problems-class-12-chemistry-surface-chemistry-2

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Surface Chemistry

Q 1.

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

Q 2.

Why is the ester-hydrolysis slow in the beginning and becomes faster after sometime?

Q 3.

Why is chemisorption referred to as activated adsorption?

Q 4.

What type of solutions are formed on dissolving different concentrations of soap in water?

Q 5.

What role does adsorption play in heterogeneous catalysis?

Q 6.

Give four examples of heterogeneous catalysis.

Q 7.

Gelatin which is a peptide added in ice-creams. What can be its role?

Q 8.

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 9.

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

Q 10.

Explain what is observed
(i) when a beam of light is passed through a colloidal sol.
(ii) an electrolyte, NaCI is added to hydrated ferric oxide sol.
(iii) electric current is passed through a colloidal sol.

Q 11.

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 12.

Why does physisorption decrease with the increase of temperature?

Q 13.

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

Q 14.

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 15.

What are the applications of adsorption in chemical analysis?

Q 16.

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

Q 17.

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

Q 18.

Why is it essential to wash the precipitate with water before estimating it quantitatively?

Q 19.

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

Q 20.

What happens when dialysis is prolonged?

Q 21.

What is the role of activated charcoal in gas mask used in coal mines?

Q 22.

Match the types of colloidal systems given in Column I with the name given in Column II.
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-20

Q 23.

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

Q 24.

Distinguish between the meaning of the terms adsorption and absorption. Give one example of each.

Q 25.

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

Q 26.

What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?

Q 27.

H2 gas is adsorbed on activated charcoal to a very little extent in comparison
to easily liquefiable gases due to
(a) very strong van der Waals interaction
(b) very weak van der Waals forces
(c) very low critical temperature
(d) very high critical temperature.

Q 28.

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

Q 29.

Why is chemisorption referred to as activated adsorption?

Q 30.

Why are some medicines more effective in the colloidal form?

Q 31.

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

Q 32.

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

Q 33.

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 34.

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

Q 35.

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

Q 36.

What do you understand by activation of adsorbent? How is it achieved?

Q 37.

What are enzymes? Write in brief the mechanism of enzyme catalysis.

Q 38.

Arrange the following diagrams in correct sequence of steps involved in the mechanism of catalysis, in accordance with modem adsorption theory.
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-9

Q 39.

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

Q 40.

Freundlich adsorption isotherm is given by the expression  x/m=KP1/n. Which of the following conclusions can be drawn from this expression?
ncert-exemplar-problems-class-12-chemistry-surface-chemistry-15

Q 41.

Which of the following statements are correct?
(a) Mixing two oppositely charged sols neutralizes their charges and stabilizes the colloid.
(b) Presence of equal and similar charges on colloidal particles provides stability to the colloids.
(c) Any amount of dispersed liquid can be added to emulsion without destabilizing it.
(d) Brownian movement stabilizes sols.

Q 42.

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

Q 43.

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 44.

What happens when gelatin is mixed with gold sol?

Q 45.

How does it become possible to cause artificial rain by spraying silver iodide on the clouds?

Q 46.

What is collodion?

Q 47.

Why do we add alum to purify water?

Q 48.

What happens when electric field is applied to colloidal solution?

Q 49.

What causes Brownian motion in colloidal dispersion?

Q 50.

How do emulsifying agents stabilize the emulsion?