Surface Chemistry Questions and Answer | NCERT, CLASS 12, CHEMISTRY

Surface Chemistry Questions and Answer | NCERT, CLASS 12, CHEMISTRY

Surface Chemistry is the most important part of chemistry so you have to look on these questions are prepared by our live learns team for all the competitive exams. here the bsc chemistry Class 12 all chemistry questions and answer for you full of free pdf format also available here.


1. If both the dispersed phase and dispersion medium are liquid, then it is called as……

Ans. emulsion

2. What do you mean by lyophilic and lyophobic colloid ?

Ans. The colloid in which the dispersed phase has affinity towards dispersion medium is called as lyophilic the colloid. The colloid in which the dispersed phase has no affinity towards the dispersion medium is called lyophobic colloid.

3. Milk is an example of

Ans. emulsion

4. What is peptisation ?

Ans. The process of converting a freshly prepared precipitate into coloidal form by adding a suitable electrolyte is called peptisation.

5. What is dialysis?

Ans. It is the process of separation of colloidal particles from crystalloids by means of a membrane.

6. How can you prepare colloidal sulphur ?

Ans. Colloidal sulphur can be prepared by passing

H²S gas through a solution of nitric acid or bromine water or sulphur dioxide.

  2H²S+SO²>2H²0+3S(colloidal sulphur)

7. What happens when FeCl³ solution is added drop wise to hot water ?

Ans. Colloidal solution of ferric hydroxide is formed.

FeCl³ +3H²O -> Fe(OH)³ +3HCFl


8. The zig-zag motion of colloidal particles in colloidal solution is called as

Ans. Brownian movement

9. Scattering of light radiation by colloidal particles for which path of the beam is becomes visible is called as

Ans. Tyndal effect

10. Tyndal effect is the ____property of colloidal solution.

Ans. optical

Surface chemistry part 02

11. The purification of blood by artificial kidneys is based on the process of

Ans. dialysis.

12. What is difference between sol and emulsion

Ans. Sol is a colloidal solution of solid disperssed in a liquid.

Emulsion Is a colloidal solution of liquid dispersed in a liquid.

13. How does chemisorption of gas vary with temperature ?

Ans. It first increases and then decreases with rise in temperature.

14. Write the dispersed phase and dispersion medium in froth.

Ans. Dispersed phase is gas while dispersion medium is liquid.

15. What is aerosol ?

Ans.Dispersion of liquid or solid particles in a gas

is called aerosol. e.g. smoke and fog.

16. Most of the catalysts are used in powdered form. Explain.

Ans. In powdered form surface area is more, which can adsorb more reactant molecules giving the product.

17. How does potash alum purify water?

Ans. Potash alum (K²SO⁴ .AL² (SO⁴),

³ .24H²0) is an electrolyte. It coagulates the impurities present in water, which can be removed by filtration.

18. A lump of charcoal and powdered charcoal which will adsorb more gas?

Ans. Powdered charcoal will adsorb more gas due to its more surface area.

19. What is Brownian movement ?

Ans. The zig-zag motion of colloidal particles in a solution is called the Brownian movement. It is due to unequal bombardment of the molecules of dispersion medium on the colloidal particles.

20. What are micelles ?

Ans. Micelles are the substances which behave as

normal electrolyte at low concentration while behave as colloidal particles at higher concentration due to association. e.g. soap solution.

Surface chemistry Part 03

21. Colloidal solution can be distinguished from a true solution by

Ans. Tyndal effect

22. The precipitation of a colloidal solution by adding excess of an electrolyte is called as

Ans. Coagulation or flocculation

23. What is electrophoresis?

Ans. The phenomenon of movement of colloidal particles towards oppositely charged electrodes, under the influence of electric field is called as electrophoresis.

24. The phenomenon of movement of dispersion medium towards oppositely charged electrodes under the influence of electric field is called as

Ans. electro osmosis

25. Butter is an example of____

Ans. Water in oil type of emulsion.

26. Mixture of any two immiscible liquids is called as

Ans. emulsion

27. The colloidal system in which dispersed phase is liquid and dispersion medium is solid is called as

Ans. gel

28. What is adsorption?

Ans. The phenomenon of adhering of the gas or

liquid molecules on the surface of a solid is called as Adsorption. It is a surface phenomenon.

29. What is peptisation ?

Ans. The process of transforming back a precipitate into colloidal form is called peptisation

30. Adsorption of gases on a solid surface is called as____? 

Ans. Occlusion

Surface chemistry Part 04

31. How can you prepare colloidal gold___?

Ans. When auric chloride solution is treated with stannous chloride solution colloidal gold is formed.

3SnCl² +2AuCl³ ->3SnCl⁴ +2Au

32. Colloidal solution of graphite in water is called as

Ans. Aquadag

33. What is the cause of origin of charge on colloidal particles?

Ans. The charge on colloidal particles is due to preferential adsorption of ions on their surface. If +ve ions get adsorbed, then sol particles acquire a positive charge. e.g. Ferric hydroxide sol acquires the charge due to adsorption of Fes’ ‘ ions on its surface.

34. Arrange the ions in increasing order of their flocculating power. (Al³+, Ba² Na+)

Ans. The increasing order of flocculating power is Na+ < Ba²+ <Al³+

35. How is the protective action of colloids related to gold numbers ?

Ans. Smaller the gold number, greater is the protective action of the protective colloid to prevent coagulation.

36. What is the difference between adsorption and absorption ?

Ans. Adsorption is a surface phenomenon, in which gas or liquid molecules are concentrated only on the surface of a solid e.g. water vapours are adsorbed by silica gel.

In Absorption the gas or liquid molecules are uniformly distributed throughout the body of solid or liquid. e.g. water vapours are absorbed by anhydrous calcium chloride.

37. Write two factors affecting adsorption of a gas on the solid surface.

Ans. Nature of the gas Easily liquified gases like CO², NH², HCl are adsorbed to a greater extent than H², N², 0² etc. 

Pressure & temperature Increase in pressure and decrease in temperature increases the rate of adsorption.

38. What is a catalyst ?

Ans. Catalyst is a substance which change the rate

of reaction and itself remains unchanged even after Completion of reaction.

39. What is the dispersed phase and dispersion medium in milk ? 

ans.  Dispersed phase = fat 

         Dispersed Medium = Water 

40. Give one example each of oil in water and water in oil type emulsion.


          Water in oil – Butter, cold cream. 

          Oil in water milk, vanishing cream.

Surface chemistry Part 05

41. Out of sulphur sol and starch sol which forms multimolecular colloids ?

Ans. Sulphur sol forms multimolecular colloids.

42. Give an example of heterogeneous catalysis.

Ans. In Haber’s process Iron (solid) is used as a catalyst for manufacture of NH, from Na) and H2(g Nickel is used for hydrogenation of oils.

43. Write two uses of emulsions.

Ans. Concentration of sulphide ores by forth the floatation process and cleaning action of soap are the uses of emulsions.

44. What is the difference between hydrosol and alcosol?

Ans. The colloidal solution of solid in water is called hydrosol, while in alcohol is called alcosol

45. Out of starch and gelatin,it has a minimum gold number.

Ans. gelatin

46. Between gold sol and gelatin in water which is hydrophobic sol ?

Ans. Gold sol is hydrophobic in nature.

47. Starch sol is an example of a type of colloid.

Ans. Macromolecular

48. Define Hardy-Schulze Rule

Ans. According to this rule – higher the charge of The flocculating ion greater is its coagulating power.

49. Define Gold number’.

Ans. It is the number of mg of the protective colloid which prevents coagulation of 10ml of a given gold sol when 1ml of 10% solution of NaCl is added to it.

50. Soap sol is an example of a type of colloid.

Ans. Associated

Thank you

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