1. OBJECTIVE QUESTIONS
FOR
NEET AIIMS JIPMER

2. CHEMISTRY
COLLOIDAL STATE
SET 1
MCQ’S

3. Q1. The values of colligative properties of colloidal solution are of small order in comparison to those shown by true solutions of same concentration because of colloidal particles
Exhibit enormous surface area
Remain suspended in the dispersion medium
From lyophilic colloids
Are comparatively less in number

4. ANSWER (D) EXPLANATION
The values of colligative properties of colloidal solution are of small order in comparison to these shown by true solutions of same concentration because of colloidal particles are comparatively less in number.

5. Q2. Fog is a colloidal solution of
Liquid particles dispersed in a gas
Gaseous particles dispersed in a liquid
Solid particles dispersed in a liquid
Solid particles dispersed in a gas

6. ANSWER (A) EXPLANATION
Fog is liquid dispersed in gas, a class of colloidal system

7. Q3. A gel is
A liquid mass of a lyophilic sol in which all the dispersion medium has penetrated into the sol particles
Like an emulsion which is stabilished by adding emulsifying agent
A semirigid mass of a lyophobic sol in which all the dispersion medium has penetrated into the sol particles
A semirigid mass of a lyophilic sol in which the dispersion medium has penetrated into the sol particles

8. ANSWER (D) EXPLANATION
A gel is liquid dispersed in solid. E.g. cheese

9. Q4. A freshly prepared Fe(OH)3 precipitate is peptised by adding FeCl3 solution. The charge on the colloidal particles is due to preferential adsorption of
Br- ion
Fe3+ ion
OH- ion
Ba2+ ion

10. ANSWER (B) EXPLANATION
Solution particle adsorbs common ion present in the medium.

11. Q5. Cod liver oil is Fat dispersed in water Water dispersed in fat
Water dispersed in oil
Fat dispersed in fat

12. ANSWER (C) EXPLANATION
It is water dispersed in oil type emulsion.

13. Q6. The spontaneous outcome of internal liquid from gets is called
Syneresis
Thixotropy
Swelling
None of these

14. ANSWER (A) EXPLANATION
It is a property of gel
Syneresis - in chemistry, is the extraction or expulsion of a liquid from a gel, as when serum drains from a contracting clot of blood. Another example of syneresis is the collection of whey on the surface of yogurt.

15. Q7. Addition of lyophilic solution to the emulsion. Forms
A protective film around the dispersed phase
A protective film around the dispersion medium
An aerosol
True solution

16. ANSWER (A) EXPLANATION
surface phase reaction takes place.

17. Q8. The isoelectric point of a colloidally dispersed material is the pH value at which
The dispersed phase migrate in an electric field
The dispersed phase does not migrate in an electric field
The dispersed phase has pH equal to 7
The dispersed phase has pH equal to zero

18. ANSWER (B) EXPLANATION
The hydrogen ion concentration at which the colloidal particles have neither positive nor negative charge Is known as isoelectric point.
Therefore, at isoelectric point, particles do not migrate under the influence of electric field.

19. Q9. Lyophilic solution are more stable than lyophobic solutions because
The colloidal particles have positive charge
The colloidal particles have negative charge
The colloidal particles are solvated
There is strong electrostatic repulsions between the negatively charged colloidal particles

20. ANSWER (C) EXPLANATION
Lyophillic colloids are more stable due to solvation

21. Q10. Which of the following is not the property of hydrophilic solutions ?
High concentration of dispersed phase can be easily obtained
Coagulation is reversible
Viscosity and surface tension are nearly the same as that of water
The charge of the particles depends on the pH of the medium and it may be positive, negative or zero

22. ANSWER (C) EXPLANATION
Viscosity is higher than that of dispersion medium (water) while surface tension is usually lower than that of dispersion medium (water).

23. Q11. Which one is hydrophobic in nature ?
Gelatin
Sulphur
Starch
Protein

24. ANSWER (B) EXPLANATION
Inorganic sols are usually hydrophobic in nature.

25. Q12. Lyophilic sols are Irreversible sols
Prepared from inorganic compounds
Coagulated by adding electrolytes
Self – stabilising

26. ANSWER (d) EXPLANATION
Lyophilic sols are self stabilizing because these sols are reversible and are highly hydrated in the solution.

27. Q13. The critical micelle concentration (CMC) is
The concentration at which micellisation starts
The concentration at which the true solution is formed
The concentration at which one molar electrolyte is present per 1000 g of the solution
The concentration at which ∆𝐻=0

28. ANSWER (A) EXPLANATION
It is the minimum concentration at which surfactant molecules undergo aggregation.

29. Q14. Which type of molecules form micelles ?
Non – polar molecules
Polar molecules
Surfactant molecules
Salt of weak acid and weak base

30. ANSWER (C) EXPLANATION
Surfactant molecules from micelles.

31. Q15. During the micelle formation,
∆H= +ve, ∆S= +ve
∆H= −ve, ∆S= −ve
∆H= ve, ∆S= +ve
∆H= +ve, ∆S= −ve

32. ANSWER (C) EXPLANATION
∆H=negative, ∆S=positive

33. Q16. Micelles form only
Below the critical micelle concentration (CMC) and below the kraft temperature (TK)
Above CMC and below the TK
Above the CMC and above the Tk
Below the CMC and above the Tk

34. ANSWER (C) EXPLANATION
Micelle formation takes place above a particular temperature, called kraft temperature (TK) and above a particular concentration, called critical micelle concentraction (CMC).

35. Q17. Micelles are Emulsion cum gel Associated colloids
Adsorbed catalysis
Ideal solutions

36. ANSWER (B) EXPLANATION
Micelles are associated colloids.

37. Q18. The colloidal sol formed from SnO2 in acidic and basic medium respectively are

38. ANSWER (C) EXPLANATION
In acidic medium, Sn4+ ion is formed which is preferentially adsorbed on SnO2 giving positively charged colloidal sol.
In basic medium, 𝑆𝑛𝑂 3 2− is formed which is preferentially adsorbed on SnO2, giving negatively charged colloidal sol.

39. Q19. A particle of radius 1 cm is broken to form colloidal particles of radius 1000 Å. The number of colloidal particles produced are
1015
6.023× 10 23
1012
1010

40. ANSWER (A) EXPLANATION

41. Q20. Separation of colloidal particles from those of molecular dimensions by means of electric current is known as
Electroosmosis
Electrophoresis
Electrodialysis
Electrolysis

42. ANSWER (B) EXPLANATION
In electrophoresis, charged sol particles move towards opposite electrodes.