1. OBJECTIVE QUESTIONS
FOR
NEET AIIMS JIPMER

2. CHEMISTRY
COLLOIDAL STATE
SET 2
MCQ’S

3. Q1. The Brownian movement is due to
Enthalpy change during the formation of colloids
Attractive force between the colloidal particles and the molecules of dispersion medium
The impact of molecules of the dispersion medium on the colloidal particles
The movement of positively charged colloidal particles to negatively charged particle

4. ANSWER (C) EXPLANATION
Brownian movement is zig – zag motion of suspended particles.

5. Q2. Which of the following process is responsible for the formation of delta at a place where rivers meet the sea ?
Emulsification
Colloidal formation
Coagulation
Peptisation

6. ANSWER (C)
EXPLANATION
The process is responsible for the formation of delta at a place where rivers meet the sea is coagulation.

7. Q3. Which of the following ions have minimum value of flocculating power ?

8. ANSWER (A) EXPLANATION

9. Q4. Match the following and choose the correct option.
Column I
Column II
Protective colloid
FeCl3 + NaOH
B. Liquid – liquid colloid
2. Lyophilic colloids
C. Positively charged colloid
3. Emulsion
D. Negatively charged colloid
4. FeCl3 + hot water
(A)
(B)
(C)
(D)

10. ANSWER (C) EXPLANATION
A 2 , B 3, C 4, D  1

11. Q5. Which of the following statements is correct for Tyndall effect ?
Scattering and polarizing of light by small suspended particles is called Tyndall effect
Tyndall effect of colloidal particles is due to dispersion of light
Tyndall effect is due to refraction of light
Zig – zag motion of suspended particles

12. ANSWER (A) EXPLANATION
When a beam of lights is passed through a colloidal solution, its path becomes visible. This is known as Tyndall effect.

13. Q6. In a coagulating experiment, 5 mL of As2S3 is mixed with distilled water and 0.2 M solution of an electrolyte AB, so that the total volume is 20 mL. All solutions containing 5.4 mL of AB coagulate within 2 min. The flocculation value of AB (in millimole) is 5 50 54
None of these

14. ANSWER (C) EXPLANATION
Flocculation value is the amount of electrolyte, in millimoles required to bring about complete coagulation of one litre of colloidal solution.

15. Q7. Peptisation involves
Precipitation of colloidal particles
Disintegration of colloidal aggregates
Evaporation of dispersion medium
Impact of molecules of the dispersion medium on the colloidal particles

16. ANSWER (C) EXPLANATION
Peptisation involves disintegration of colloidal aggregates.

17. Q8. Which of the following will show Tyndall effect ?
Aqueous solution of soap below critical micelle
Aqueous solution of soap above critical micelle concentration
Aqueous solution of sodium chloride
Aqueous solution of sugar

18. ANSWER (B) EXPLANATION
Aqueous solution of soap above critical micelle concentration show Tyndall effect.

19. Q9. When 9. 0 mL of arsenious sulphide sol and 1. 0 mL of 0
Q9. When 9.0 mL of arsenious sulphide sol and 1.0 mL of 0.1 M BaCl2 are mixed, tubidity due to precipitation just appears after 2 h. the affective ion and its coagulation value respectively are
Cl-, 10 millimol L-1
Cl- 20 millimol L-1
Ba2+, 10 millimol L-1
Ba2+, 20 millimol L-1

20. ANSWER (C) EXPLANATION
As2S3 sol is negatively charged due to preferential adsorption of S2- ions by As2S3 particles. Hence, cation of largest valency (i.e. Ba2+) would be most effective in causing coagulation of the sol.
10 mL (9.0 mL of As2S3 and 1.0 mL BaCl2) of As2S3 requires BaCl2 for coagulation =1.0× 10 −4 mol
1000 mL of As2S3 requires BaCl2 for coagulation

21. Q10. The coagulation values of AlCl3 and NaCl are 0
Q10. The coagulation values of AlCl3 and NaCl are and 52 respectively. The ratio of Coagulating powers of both will be
0.093 : 1
52 : 1
559 : 1
1.788 : 1

22. ANSWER (C) EXPLANATION
As coagulating power is inversely proportional to coagulation value, the ratio of their coagulating powers will be

23. Q11. The dispersed phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged, respectively. Which of the following statements is not correct ?
Coagulation in both sols can be brought about by electrophoresis
Mixing the sols has no effect
Sodium sulphate solution causes coagulation in both sols
Magnesium chloride solution coagulates the gols sol more readily than the iron (III) hydroxide sol

24. ANSWER (B) EXPLANATION
Mixing the sols together can cause coagulation, since the charges are neutralized.

25. Q12. Gold number is the index for
Protective power of lyophilic colloid
Purity of gold
Metallic gold
Electroplated gold

26. ANSWER (A) EXPLANATION
Protective character of various lyophilic substances is expressed in terms of gold number.

27. Q13. Hardy –Schulze law states that
Larger the charge on the coagulating ions, greater is its coagulating power, having opposite sign of solution
Solution must have zero gold number
Dispersed phase and sispersion medium must be of the same sign
Micelles coagulate in the presence of surfactants

28. ANSWER (A) EXPLANATION
Definition of Hardy – Schulze law

29. Q14. When dilute aqueous solution of AgNO3 (excess) is added to KI solution, positively charged sol particles of AgI are formed due to adsorption of ion K+
Ag+ I+
NO 3 −

30. ANSWER (B) EXPLANATION
Sol particles possess the tendency to adsorb preferentially the common ion present in solution.

31. Q15. Gold numbers of protective colloids A, B, C and D are 0. 50, 0
Q15. Gold numbers of protective colloids A, B, C and D are 0.50, 0.01, 0.10 and 0.005, respectively. The correct order of their protective powers is
D < A < C < B
C < B < D <A
A < C < B < D
B < D < A < C

32. ANSWER (C) EXPLANATION
Higher the gold number, lesser will be the protective power of colloid.

33. Q16. Which of the following statements in incorrect ?
Emulsions are prepared by shaking two liquid components, say oil and water and adding some emulsifying agent
Water in oil emulsions are formed when the emulsifying agent at the interface is chiefly on the water phase
Water in oil emulsions are formed when the emulsifying agent at the interface is chiefly in the oil phase
Gems and gels mixed together to give emulsions

34. ANSWER (D) EXPLANATION
Gems are solid and gels are semisolid. This mixture will not form emulsion.

35. Q17. In the following emulsions :
I is of oil in water type and II is of water in oil type
I is of water in oil type and II is of oil in water type
Both are of oil in water type
Both are of water in oil type

36. ANSWER (A) EXPLANATION
In the given emulsions, I is oil in water type and II is water in oil type.

37. Q18. An oil soluble dye is shaken with the given emulsion under study
Q18. An oil soluble dye is shaken with the given emulsion under study. We observe that whole background appears coloured. This indicates that emulsion is
Water in oil type
Oil in water type
Liquid under study is pure oil
Liquid under study is pure water

38. ANSWER (A) EXPLANATION
Whole background appears coloured in case of water in oil type emulsion as dye is oil soluble.

39. Q19. An oil soluble dye is shaken with the given emulsion under study
Q19. An oil soluble dye is shaken with the given emulsion under study. We observe coloured drops when seen under microscope. Thus, emulsion is
Water in oil type
Oil in water type
Liquid under study is pure oil
Liquid under study is pure water

40. ANSWER (B) EXPLANATION
When oil soluble dye is shaken with oil in water type emulsion coloured drops are observed.

41. Q20. Select the incorrect statement(s)
Surface active agents like soaps and synthetic detergents are micelles
Soaps are emulsifying agents
C17 H35 (hydrocarbon part) and – coo- (carboxylate) part of stearate ion (C17H35COO-) both are hydrophobic
All of the above are incorrect statements

42. ANSWER (C) EXPLANATION
– COO- (carboxylate part) –Hydrophilic,
C17H35 (hydrocarbon part) – hydrophobic.