Chemistry Class 12 Chapter 5

1. Which of the following is less than zero during adsorption ?

(a) ΔG

(b) ΔS

(c) ΔH

(d) All of these

Ans (D)

2. Which of the following is a property of physisorption ?

(a) High specificity

(b) Irreversibility

(c) Non-specificity

(d) None of these

Ans (C)

3. Which of the following statement is not correct about physisorption ?

(a) It is a reversible process

(b) It requires less heat of adsorption

(c) It requires activation energy

(d) It takes place at low temperature

Ans (C)

4. The incorrect statement about physical adsorption is

(a) it lacks specificity

(b) it is generally reversible

(c) porous surfaces are good adsorbent

(d) heat of adsorption is quite high

Ans (D)

5. Which is correct in case of van der Waals adsorptions ?

(a) High temperature, low pressure

(b) High temperature, high pressure

(c) Low temperature, low pressure

(d) Low temperature, high pressure

Ans (D)

6. Which, of the following gases is least absorbed on charcoal ?

(a)HCl

(b) NH3

(c) O2

(d) CO2

Ans (C)

7. Which of the following is not characteristic of chemisorption ?

(a) Adsorption is specific

(b) Heat of adsorption is of the order of 200 kJ mol-1

(c) Adsorption is irreversible

(d) Adsorption may be multimolecular layers

Ans (D)

8. Which of the following is not correct regarding the adsorption of a gas on the surface of solid ?

(a) On increasing pressure, adsorption keeps on increasing

(b) Enthalpy and entropy changes are negative

(c) Chemisorption is more specific than physisorption

(d) It is a reversible reaction

Ans (A)

9. At low pressure, the fraction of the surface covered follows

(a) zero-order kinetics

(b) first order kinetics

(c) second order kinetics

(d) fractional  order kinetics

Ans (B)

10. Which of the following gases present in a polluted area will be adsorbed most easily on the charcoal gas mask ?

(a) H2

(b) O3

(c) N2

(d) SO2

Ans (D)

11. Which of the following is application of adsorption in chemical analysis

(a) Adsorption indicators

(b) Thin layer chromatography

(c) Qualitative analysis

(d) All of these

Ans (D)

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

(a) Shape selective catalysts

(b) Adsorption of pine oil on sulphide ore particles

(c) Adsorption of pine oil on impurities

(d) Production of heat in the process of exothermic reaction

Ans (B)

13. Which of the following can adsorb larger volume of hydrogen gas ?

(a) Finely divided platinum

(b) Colloidal solution of palladium

(c) Small pieces of palladium

(d) A single metal surface of platinum

Ans (B)

14. Which kind of catalysis can be explained on the basis of adsorption theory ?

(a) Homogeneous catalysis

(b) Heterogeneous catalysis

(c) Negative catalysis

(d) Auto catalysis

Ans (B)

15. The oxide of nitrogen which acts as a catalyst in lead chamber proces is …………

(a) NO

(b) NO2

(c) N2O4

(d) N2O5

Ans (A)

16. Shape-selective catalysis is a reaction catalysed by …………….

(a) zeolites

(b) enzymes

(c) platinum

(d) Ziegler-Natta catalyst

Ans (A)

17. The activity of an enzyme becomes ineffective ……….

(a) at low temperature

(b) at atmospheric pressure

(c) at high temperature

(d) in aqueous medium

Ans (C)

18. The size of colloidal particles ranges between ………….

(a) 10-7 – 10-9cm

(b) 10-9 -101 cm

(c) 10-5 – 10-7cm

(d) 10-2 – 10-3cm

Ans (C)

19. Which of the following will not form a colloidal system ?

(a) Solid-gas

(b) Liquid-gas

(c) Gas-gas

(d) Gas-liquid

Ans (C)

20. Fog is an example of colloidal system of ………….

(a) liquid in gas

(b) gas in liquid

(c) solid in gas

(d) gas in solid

Ans (A)

21. A colloidal system in which liquid is dispersed phase and solid is dispersion medium is classified as ………….

(a) gel

(b) sol

(c) emulsion

(d) aerosol

Ans (A)

22. Which of the following example is correctly matched ?

(a) Butter – gel

(b) Smoke – emulsion

(c) Paint – foam

(d) Milk – aerosol

Ans (A)

23. Which of the following factors contribute towards higher stability of lyophilic colloid ?

(a) Charge on their particles

(b) Attractive forces between particles

(c) Small size of their particles

(d) High solvation due to a layer of dispersion medium

Ans (D)

24. A lyophobic colloid cannot be formed by ………….

(a) mixing dispersed phase and dispersion medium

(b) chemical reactions like hydrolysis

(c) exchange of solvent

(d) geptisation

Ans (A)

25. Which of the following is not correctly matched ?

(a) Gelatin – Lyophilic colloid

(b) Gold sol – Lyophilic colloid

(c) Arsenious sulphide – Lyophobic colloid

(d) Ferric hydroxide – Lyophobic colloid

Ans (B)

26. The substances which behave as colloidal solutions at higher concentration are called ………….

(a) associated colloids

(b) multimolecular colloids

(c) macromolecular colloids

(d) protective colloids

Ans (A)

27. The formation of micelles takes place only above …………..

(a) critical temperature

(b) Kraft temperature

(c) inversion temperature

(d) absolute temperature

Ans (B)

28. The critical micelle concentration (CMC) is defined as…………….

(a) the concentration at which micellization starts

(b) the concentration at which micelle starts behaving like an electrolyte

(c) the concentration at which dispersed phase is separated from dispersion medium

(d) the concentration at which a colloid is converted to suspension

Ans (A)

29. Soap mixed with water below critical micelle concentration behaves as

(a) associated colloid

(b) macromolecular colloid

(c) normal electrolytic solution

(d) multimolecular colloid

Ans (C)

30. White of an egg whipped with water acts as …………………

(a) macromolecular colloid

(b) associated colloid

(c) molecular colloid

(d) normal electrolytic solution

Ans (A)

31. Which of the following is not a method of removing impurities from a colloidal sol ?

(a) Electrodialysis

(b) Ultrafiltration

(c) Ultra centrifugation

(d) Distillation

Ans (D)

32. Tyndall effect is not observed in ………………

(a) smoke

(b) emulsions

(c) sugar solution

(d) gold sol

Ans (C)

33. Which of the following systems will show Tyndall effect ?

(a) Aqueous solution of sodium chloride

(b) Aqueous solution of aluminium hydroxide

(c) Aqueous solution of glucose

(d) Aqueous solution of urea

Ans (B)

34. Which of the following is not an explanation for the origin of charge on the colloidal particles ?

(a) Due to frictional electrification

(b) Due to dissociation of surface molecules

(c) Due to electrophoresis

(d) Due to selective adsorption of ions

Ans (C)

35. Movement of dispersion medium under the influence of electric field is known as ……………

(a) electrodialysis

(b) electrophoresis

(c) electroosmosis

(d) cataphoresis

Ans (C)

36. Why is alum added to water containing suspended impurities ?

(a) To make a colloidal solution

(b) To coagulate the suspended impurities

(c) To remove impurities of calcium and magnesium

(d) To protect the colloidal solution from getting precipitated

Ans (B)

37. Which of the following acts as the best coagulating agent for ferric hydroxide sol ?

(a) Potassium ferrocyanide

(b) Potassium chloride

(c) Potassium oxalate

(d) Aluminium chloride

Ans (A)

38. Why is gelatin mixed with gold sol ?

(a) Gold sol is lyophobic sol, gelatin acts as stabilising agent

(b) Gold sol is lyophilic sol, gelatin acts as stabilising agent

(c) Gelatin produces negative charge on gold particles in gold sol

(d) Gelatin helps gold sol to get its critical micelle concentration

Ans (A)

39. Which of the following is not a method for coagulation of lyophobic sols ?

(a) By electrophoresis

(b) By mixing oppositely charged sols

(c) By adding electrolyte

(d) By adding a protective colloid

Ans (D)

40. What happens when a lyophilic sol is added to a lyophobic sol ?

(a) Lyophilic sol is protected

(b) Lyophobic sol is protected

(c) Both the sols are coagulated

(d) Electrophorsis takes place

Ans (B)

41. Which of the following is not an example of an emulsifying agent ?

(a) Proteins

(b)Gums

(c) Soaps

(d) Electrolytes

Ans (D)

42. The separation of an emulsion into its constituent liquids is known as

(a) emulsification

(b) protection of colloid

(c) coagulation

(d) demulsification

Ans (D)

43. Which of the following processes does not occur at the interface of phases ?

(a) Crystallisation

(b) Heterogeneous catalysis

(c) Homogeneous catalysis

(d) Corrosion

Ans (C)

44. At the equilibrium position in the process of adsorption …………

(a) ΔH > 0

(b) ΔH = TΔS

(c) ΔH>TΔS

(d) ΔH<TΔS

Ans (B)

45. Which of the following interfaces cannot be obtained ?

(a) Liquid-Liquid

(b) Solid-Liquid

(c) Liquid-Gas

(d) Gas-Gas

Ans (D)

46. The term ‘sorption’ stands for………………

(a) absorption

(b) adsorption

(c) both absorption and adsorption

(d) desorption

Ans (C)

47. Which of the following is not a favourable condition for physical adsorption ?

(a) High pressure

(b) Negative ΔH

(c) Higher critical temperature of adsorbate

(d) High temperature

Ans (D)

48. Physical adsorption of a gaseous species may change to chemical adsorption with……………

(a) decrease in temperature

(b) increase in temperature

(c) increase in surface area of adsorbent

(d) decrease in surface area of adsorbent

Ans (B)

49. Which of the following is an example of absorption ?

(a) Water on silica gel

(b) Water on calcium chloride

(c) Hydrogen on finely divided nickel

(d) Oxygen on metal surface

Ans (B)

50. At high concentration of soap in water, soap behaves as ……..

(a) molecular colloid

(b) associated colloid

(c) macromolecular colloid

(d) lyophilic colloid

Ans (B)

51. Freshly preparad precipitate sometimes gets converted to colloidal solution by …………..

(a) coagulation

(b) electrolysis

(c) diffusion

(d) peptisation

Ans (D)

52. Which of the following process is responsible for the formation of delta at a place where rivers meet the sea ?

(a) Emulsification

(b) Colloid formation

(c) Coagulation

(d) Peptisation

Ans (C)

53. Which of the following process is not responsible for the presence of electric charge on the sol particles ?

(a) Electron capture by sol particles

(b) Adsorption of ionic species from solution

(c) Formation of Helmholtz electrical double layer

(d) Adsorption of ionic species from solution

Ans (D)