TRB BT Assistant - Surface Chemistry and Colloids Question Bank with Options

1. Which of the following is a difference between true solutions and colloidal solutions?

A) True solutions do not show Tyndall effect, while colloidal solutions do.

B) True solutions show Brownian movement, while colloidal solutions do not.

C) The dispersed particles in true solutions are larger than those in colloidal solutions.

D) True solutions are always colored, while colloidal solutions are colorless.

2. When a gas is adsorbed on a solid surface, the entropy of the gas:

A) Increases

B) Decreases

C) Remains unchanged

D) Becomes zero

3. The formation of a colored layer on the surface of a metal when exposed to air is an example of:

A) Absorption

B) Adsorption

C) Diffusion

D) Oxidation

4. What is the role of activated charcoal in gas masks?

A) To absorb moisture from the air.

B) To adsorb poisonous gases from the air.

C) To catalyze the oxidation of harmful gases.

D) To absorb oxygen for breathing.

5. The formation of micelles by soap molecules in water above the critical micelle concentration (CMC) is an example of:

A) Adsorption

B) Colloid formation

C) Emulsification

D) Coagulation

6. Lyophobic colloids are generally:

A) Stable and easily prepared

B) Unstable and require special methods for preparation

C) Less stable than lyophilic colloids

D) Not affected by electrolytes

7. Which of the following is an example of a lyophilic colloid?

A) Metal sols

B) Sulfur sol

C) Starch sol

D) Arsenic sulfide sol

8. Emulsifiers are substances that help stabilize emulsions. They work by:

A) Increasing the interfacial tension between the two liquids.

B) Decreasing the interfacial tension and forming a protective layer.

C) Causing the two liquids to separate faster.

D) Reacting chemically with one of the liquids.

9. Catalysis is often explained in terms of surface chemistry. The catalytic activity of a solid catalyst is due to:

A) Its bulk properties

B) The presence of free valencies on its surface

C) Its high density

D) Its low melting point

10. Which of the following is a common application of adsorption?

A) Production of refrigeration

B) Production of high vacuum

C) Purification of gases

D) All of the above

11. What is an 'aerosol' in the context of colloids?

A) A liquid dispersed in a solid.

B) A solid dispersed in a liquid.

C) A liquid dispersed in a gas.

D) A gas dispersed in a liquid.

12. Ultrafiltration is a technique used to separate colloidal particles from the dispersion medium by using a filter with pores of specific size. These pores are:

A) Larger than colloidal particles

B) Smaller than colloidal particles but larger than dissolved molecules

C) Smaller than dissolved molecules

D) Of a size comparable to atoms

13. The process of removing dissolved impurities from a colloidal solution by diffusion through a semi-permeable membrane is called:

A) Ultrafiltration

B) Electroosmosis

C) Dialysis

D) Electrophoresis

14. Purification of colloidal solutions from soluble impurities is achieved by:

A) Dialysis

B) Centrifugation

C) Ultrafiltration

D) All of the above

15. The process of converting a precipitate into a colloidal solution by shaking it with a suitable electrolyte in the presence of a small amount of a new electrolyte is called:

A) Peptization

B) Coagulation

C) Dialysis

D) Electroosmosis

16. Which method is typically used to prepare colloids like sulfur or arsenic sulfide?

A) Oxidation

B) Reduction

C) Hydrolysis

D) Double decomposition

17. Which of the following is a method for preparing colloids?

A) Condensation methods

B) Oxidation

C) Reduction

D) All of the above

18. What is the term for the formation of a gel from a sol?

A) Coagulation

B) Gelation

C) Emulsification

D) Peptization

19. According to the Hardy-Schulze rule, for the coagulation of a positive colloid, the coagulating power of anions increases in the order:

A) Cl- < SO4(2-) < PO4(3-)

B) PO4(3-) < SO4(2-) < Cl-

C) NO3- < Br- < I-

D) F- < Cl- < Br-

20. Hardy-Schulze rule states that for the coagulation of a negative colloid, the coagulating power of cations increases in the order:

A) Na+ < Mg2+ < Al3+

B) Al3+ < Mg2+ < Na+

C) Na+ < K+ < Rb+

D) Ca2+ < Sr2+ < Ba2+

21. The process of destabilizing a colloidal solution by causing the dispersed particles to aggregate and settle down is called:

A) Coagulation or Flocculation

B) Dispersion

C) Emulsification

D) Solvation

22. When an electric field is applied across a colloidal solution, the charged colloidal particles move towards the oppositely charged electrode. This process is called:

A) Tyndall effect

B) Brownian movement

C) Electrophoresis

D) Coagulation

23. Colloidal particles carry an electric charge. This charge can be positive or negative. This phenomenon is known as:

A) Electrophoresis

B) Electroosmosis

C) Colloidal charge

D) Coagulation

24. Why do colloidal solutions exhibit the Tyndall effect, while true solutions do not?

A) Colloidal particles are smaller than the wavelength of visible light.

B) Colloidal particles are larger than the wavelength of visible light and scatter it.

C) True solutions contain larger particles that absorb light.

D) True solutions have a higher refractive index.

25. The Tyndall effect is the scattering of light by colloidal particles. This effect is observed when:

A) The wavelength of light is smaller than the size of colloidal particles.

B) The wavelength of light is larger than the size of colloidal particles.

C) The wavelength of light is comparable to the size of colloidal particles.

D) The particles are molecularly dispersed.

26. The zigzag, random movement of colloidal particles suspended in a fluid is known as:

A) Brownian movement

B) Tyndall effect

C) Electroosmosis

D) Coagulation

27. A solid dispersed in a gas, like smoke or dust particles in air, is called a(n):

A) Aerosol

B) Solid sol

C) Emulsion

D) Foam

28. Which type of colloid is formed when a liquid is dispersed in a solid?

A) Gel

B) Emulsion

C) Sol

D) Foam

29. Fog and mist are examples of:

A) Emulsions

B) Aerosols

C) Foams

D) Sols

30. Milk is an example of which type of colloid?

A) Solid sol

B) Emulsion

C) Aerosol

D) Foam

31. An example of a 'sol' colloid is:

A) Milk

B) Paint

C) Fog

D) Pumice stone

32. Which of the following is NOT a type of colloid based on the physical state of the dispersed phase and dispersion medium?

A) Solid sol

B) Gas foam

C) Liquid aerosol

D) Solid liquid

33. Colloidal particles have a size range typically between:

A) 1 nm and 100 nm

B) 0.1 nm and 1 nm

C) 100 nm and 1000 nm

D) Less than 0.1 nm

34. What is the dispersion medium in a colloidal system?

A) The phase consisting of dispersed particles.

B) The phase in which the dispersed particles are distributed.

C) The solid component of an aerosol.

D) The liquid component of a gel.

35. In the context of colloids, what is the dispersed phase?

A) The medium in which the particles are scattered.

B) The particles that are scattered throughout the medium.

C) The continuous phase.

D) The substance that holds the particles together.

36. The Langmuir adsorption isotherm is based on a theoretical model. A key assumption of the Langmuir model is:

A) Adsorption sites on the surface are heterogeneous.

B) Adsorbed molecules can interact with each other.

C) Adsorption occurs at specific, localized sites and is reversible.

D) Adsorption is irreversible and multilayer.

37. According to the Freundlich adsorption isotherm, at very low pressures, the amount adsorbed is approximately:

A) Independent of pressure

B) Directly proportional to pressure

C) Directly proportional to the square root of pressure

D) Inversely proportional to pressure

38. The Freundlich adsorption isotherm is an empirical relationship. It is expressed as x/m = kP^(1/n). What does 'x/m' represent?

A) Pressure of the gas

B) Amount of gas adsorbed per unit mass of adsorbent

C) Adsorption equilibrium constant

D) Temperature in Kelvin

39. The adsorption of gases on solid surfaces is often described by an equation relating the amount adsorbed to the pressure at a constant temperature. This is known as:

A) Langmuir equation

B) Freundlich equation

C) Arrhenius equation

D) Nernst equation

40. Which factor generally favors physisorption?

A) High temperature

B) Low temperature

C) High pressure

D) Low pressure

41. The enthalpy change during physisorption is typically:

A) Highly exothermic (large negative value).

B) Slightly exothermic (small negative value).

C) Endothermic (positive value).

D) Zero.

42. Chemisorption is characterized by:

A) Weak van der Waals forces and low activation energy.

B) Formation of chemical bonds and high activation energy.

C) Reversibility and low enthalpy change.

D) Reversibility and dependence on pressure only.

43. Which type of adsorption involves the formation of weak van der Waals forces between adsorbate and adsorbent?

A) Chemisorption

B) Physisorption

C) Both Physisorption and Chemisorption

D) None of the above

44. What is the term for the phenomenon where substances are taken up by the bulk of another substance?

A) Adsorption

B) Absorption

C) Desorption

D) Chemisorption

45. In adsorption, the substance on whose surface accumulation occurs is termed:

A) Adsorbate

B) Adsorbent

C) Solvent

D) Solute

46. Adsorption is a process where substances accumulate on the surface of another substance. What is the substance that accumulates called?

A) Adsorbent

B) Adsorbate

C) Colloid

D) Emulsion

47. Which of the following is an example of an interface where surface chemistry is relevant?

A) A homogeneous solution.

B) A solid-gas interface.

C) A liquid-liquid mixture without separation.

D) A perfect crystal lattice.

48. What is the primary focus of surface chemistry?

A) The study of atomic nuclei and their transformations.

B) The study of chemical reactions and phenomena occurring at interfaces.

C) The study of molecular structures and bonding.

D) The study of the physical properties of bulk materials.

Surface Chemistry and Colloids - Question Bank