Surface Chemistry Quiz

Prepare for the PPSC Analytical Chemist exam with this Surface Chemistry Quiz, featuring important MCQs on adsorption, colloids, catalysts, and interfaces. Test your knowledge and boost your exam performance with expert-selected questions!

1. What is surface chemistry primarily concerned with?

a) Reactions in bulk phases
b) Processes at the interface of two bulk phases
c) Only solid-gas interactions
d) Only liquid-liquid interactions
Answer: b) Processes at the interface of two bulk phases

2. Which of the following is an example of a bulk phase combination in surface chemistry?

a) Solid-gas
b) Liquid-liquid
c) Solid-liquid
d) All of the above
Answer: d) All of the above

3. Adsorption is best described as:

a) The absorption of light by a surface
b) The adhesion of atoms, ions, or molecules to a surface
c) The dissolution of a solid in a liquid
d) The mixing of two gases
Answer: b) The adhesion of atoms, ions, or molecules to a surface

4. Absorption differs from adsorption in that absorption involves:

a) Molecules sticking to a surface
b) Molecules entering the bulk phase of a material
c) Only chemical bonding
d) Only physical bonding
Answer: b) Molecules entering the bulk phase of a material

5. Physical adsorption is characterized by:

a) Strong chemical bonds
b) Van der Waals forces and reversibility
c) Formation of monolayers
d) High specificity
Answer: b) Van der Waals forces and reversibility

6. Chemical adsorption involves:

a) Weak van der Waals forces
b) Formation of multilayers
c) Strong chemical bonding and specificity
d) No activation energy
Answer: c) Strong chemical bonding and specificity

7. Which of the following is NOT a cause of adsorption?

a) Hydrophobicity
b) Electrostatic forces
c) Chemical bonding
d) High pressure alone
Answer: d) High pressure alone

8. The enthalpy of adsorption for physisorption typically ranges between:

a) 20–40 kJ/mol
b) 200–400 kJ/mol
c) 500–600 kJ/mol
d) 1–10 kJ/mol
Answer: a) 20–40 kJ/mol

9. Chemisorption is usually:

a) Reversible
b) Non-specific
c) Irreversible
d) Multilayered
Answer: c) Irreversible

10. Which isotherm describes the relationship between adsorption and pressure at constant temperature?

a) Freundlich isotherm
b) Langmuir isotherm
c) Linear isotherm
d) All of the above
Answer: d) All of the above

11. Freundlich adsorption isotherm is expressed as:

a) ( x/m = kP )
b) ( x/m = kP^{1/n} )
c) ( x/m = k/P )
d) ( x/m = k + P )
Answer: b) ( x/m = kP^{1/n} )

12. A plot of extent of adsorption vs. temperature at constant pressure is called:

a) Adsorption isotherm
b) Adsorption isobar
c) Adsorption isostere
d) None of the above
Answer: b) Adsorption isobar

13. Which of the following is an application of adsorption?

a) Gas masks
b) Production of high vacuum
c) Chromatographic analysis
d) All of the above
Answer: d) All of the above

14. Zeolites are used as shape-selective catalysts due to their:

a) Microporous structure
b) High acidity
c) Both a) and b)
d) None of the above
Answer: c) Both a) and b)

15. ZSM-5 is a type of:

a) Zeolite
b) Enzyme
c) Protein
d) Detergent
Answer: a) Zeolite

16. The Tyndall effect is observed in:

a) True solutions
b) Colloidal solutions
c) Suspensions
d) Both b) and c)
Answer: b) Colloidal solutions

17. Colloidal particles typically range in size from:

a) <1 nm
b) 1–100 nm
c) >100 nm
d) >1 µm
Answer: b) 1–100 nm

18. Brownian motion refers to the:

a) Random movement of colloidal particles
b) Sedimentation of particles
c) Coagulation of colloids
d) None of the above
Answer: a) Random movement of colloidal particles

19. Which of the following is a lyophobic colloid?

a) Gum in water
b) Gold sol
c) Gelatin in water
d) Starch in water
Answer: b) Gold sol

20. Lyophilic colloids are:

a) Irreversible
b) Self-stabilizing
c) Formed only by metals
d) None of the above
Answer: b) Self-stabilizing

21. The process of converting a precipitate into colloidal particles is called:

a) Dialysis
b) Peptization
c) Electrophoresis
d) Coagulation
Answer: b) Peptization

22. The Hardy-Schulze law states that coagulating power depends on:

a) Temperature
b) Valency of ions
c) Pressure
d) None of the above
Answer: b) Valency of ions

23. For a negatively charged sol, the coagulating power of ions follows the order:

a) Al3+ > Ba2+ > Na+
b) Na+ > Ba2+ > Al3+
c) Ba2+ > Al3+ > Na+
d) All are equal
Answer: a) Al3+ > Ba2+ > Na+

24. Electrophoresis is used to determine:

a) Charge on colloidal particles
b) Size of colloidal particles
c) Temperature of colloids
d) None of the above
Answer: a) Charge on colloidal particles

25. The zeta potential is the potential at the:

a) Surface of the colloidal particle
b) Shear plane of the electrical double layer
c) Bulk solution
d) None of the above
Answer: b) Shear plane of the electrical double layer

26. Micelles are formed when surfactant concentration exceeds:

a) Kraft temperature
b) Critical micelle concentration (CMC)
c) Cloud point
d) None of the above
Answer: b) Critical micelle concentration (CMC)

27. The Kraft temperature is the temperature above which:

a) Micelles form
b) Soaps become ineffective
c) Colloids coagulate
d) None of the above
Answer: a) Micelles form

28. Soaps lose their cleaning action in hard water due to:

a) Formation of micelles
b) Precipitation with Ca2+ and Mg2+
c) High pH
d) None of the above
Answer: b) Precipitation with Ca2+ and Mg2+

29. The hydrophilic part of a soap molecule is:

a) Hydrocarbon tail
b) Charged head (e.g., ( \text{COO}^- ))
c) Both a) and b)
d) None of the above
Answer: b) Charged head (e.g., ( \text{COO}^- ))

30. Which of the following is NOT a type of detergent?

a) Anionic
b) Cationic
c) Neutral
d) Zwitterionic
Answer: c) Neutral

31. The process of dialysis is used to:

a) Purify colloids
b) Coagulate colloids
c) Measure particle size
d) None of the above
Answer: a) Purify colloids

32. The cloud point is associated with:

a) Non-ionic surfactants
b) Ionic surfactants
c) Lyophobic colloids
d) All of the above
Answer: a) Non-ionic surfactants

33. In chromatography, adsorption is used to:

a) Separate mixtures
b) Measure pH
c) Determine temperature
d) None of the above
Answer: a) Separate mixtures

34. The term “physisorption” refers to adsorption due to:

a) Chemical bonds
b) van der Waals forces
c) Hydrogen bonds
d) Ionic bonds
Answer: b) van der Waals forces

35. The Freundlich isotherm is valid when the plot of ( \log(x/m) ) vs. ( \log P ) is:

a) A straight line
b) A curve
c) A parabola
d) None of the above
Answer: a) A straight line

36. Which of the following is a macromolecular colloid?

a) Gold sol
b) Starch solution
c) Sulphur sol
d) Arsenious sulphide sol
Answer: b) Starch solution

37. Associated colloids form micelles only above:

a) Critical micelle concentration (CMC)
b) Kraft temperature
c) Both a) and b)
d) None of the above
Answer: c) Both a) and b)

38. Bredig’s arc method is used to prepare colloidal solutions of:

a) Proteins
b) Metals
c) Polymers
d) None of the above
Answer: b) Metals

39. Ultrafiltration differs from dialysis in that it:

a) Uses a semi-permeable membrane
b) Uses an electric field
c) Uses pressure to separate colloids
d) None of the above
Answer: c) Uses pressure to separate colloids

40. The coagulating power of an electrolyte depends on:

a) Charge of the ion (valency)
b) Size of the ion
c) Temperature
d) None of the above
Answer: a) Charge of the ion (valency)

41. Which of the following will coagulate a positively charged sol most effectively?

a) NaCl
b) K₂SO₄
c) AlCl₃
d) Na₃PO₄
Answer: d) Na₃PO₄ (highest valency anion, PO₄³⁻)

42. In electrodialysis, the purification of colloids is accelerated by:

a) Heating
b) Applying an electric field
c) Stirring
d) None of the above
Answer: b) Applying an electric field

43. The Tyndall effect is strongest in:

a) Lyophilic colloids
b) Lyophobic colloids
c) True solutions
d) Suspensions
Answer: b) Lyophobic colloids

44. Which colloid is used in gas masks for adsorption of toxic gases?

a) Gelatin
b) Activated charcoal
c) Ferric hydroxide sol
d) None of the above
Answer: b) Activated charcoal

45. The process of flocculation involves:

a) Breaking colloids into smaller particles
b) Aggregating colloidal particles
c) Changing the charge of colloids
d) None of the above
Answer: b) Aggregating colloidal particles

46. The hydrophobic tail of a soap molecule is typically:

a) A charged group (e.g., COO⁻)
b) A hydrocarbon chain
c) A metal ion (e.g., Na⁺)
d) None of the above
Answer: b) A hydrocarbon chain

47. Which component in detergents prevents redeposition of dirt on fabrics?

a) Builders (e.g., phosphates)
b) Suspension agents (e.g., CMC)
c) Bleaches
d) Fragrances
Answer: b) Suspension agents (e.g., CMC)

48. Saponification is the process of converting fats into:

a) Micelles
b) Soap and glycerol
c) Detergents
d) None of the above
Answer: b) Soap and glycerol

49. Non-ionic detergents contain:

a) No charged groups
b) Sulfonate groups
c) Quaternary ammonium groups
d) All of the above
Answer: a) No charged groups

50. The cloud point is observed in:

a) Ionic surfactants
b) Non-ionic surfactants
c) Only in lyophobic colloids
d) None of the above
Answer: b) Non-ionic surfactants

51. Which catalyst is used in petroleum industries for hydrocarbon interconversion?

a) ZSM-5
b) Activated charcoal
c) Alumina
d) None of the above
Answer: a) ZSM-5

52. The term “isostere” in adsorption refers to a plot of:

a) ( x/m ) vs. ( P ) (constant ( T ))
b) ( x/m ) vs. ( T ) (constant ( P ))
c) ( P ) vs. ( T ) (constant ( x/m ))
d) None of the above
Answer: c) ( P ) vs. ( T ) (constant ( x/m ))

53. In Freundlich isotherm, the value of ( 1/n ) ranges between:

a) 0 and 1
b) 1 and 2
c) 2 and 3
d) None of the above
Answer: a) 0 and 1

54. Which colloid is used to control humidity?

a) Silica gel
b) Arsenious sulphide sol
c) Gold sol
d) None of the above
Answer: a) Silica gel

55. The primary function of builders in detergents is to:

a) Soften water
b) Add fragrance
c) Remove stains
d) None of the above
Answer: a) Soften water

56. Which of the following is a solid aerosol?

a) Smoke
b) Fog
c) Milk
d) None of the above
Answer: a) Smoke

57. The diameter of pores in ZSM-5 is approximately:

a) 5.4–5.6 Å
b) 7.4 Å
c) 10 Å
d) None of the above
Answer: a) 5.4–5.6 Å

58. In micelles, the hydrophobic tails are oriented:

a) Outward (toward water)
b) Inward (away from water)
c) Randomly
d) None of the above
Answer: b) Inward (away from water)

59. The term “lyophobic” means:

a) Solvent-loving
b) Solvent-hating
c) Heat-loving
d) None of the above
Answer: b) Solvent-hating

60. Which of the following is NOT a property of chemisorption?

a) Monolayer formation
b) High specificity
c) Reversibility
d) High enthalpy
Answer: c) Reversibility