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Question Bank No: 1

1. Which of the following is a hydrophobic sol?

a)		Starch solution
b)		Gun solution
c)		Proetin solution
d)		Arsenious sulphide solution

2. Which of the following is less than zero during adsoption?

a)		$Δ G$
b)		$Δ S$
c)		$Δ H$
d)		All of the above

3. Which of the following can form colloidal solution with water?

a)		NaCL
b)		Glucose
c)		a suspension
d)		none of these

4. When beam of light is passed through a colloidal solution?

a)		It passes through as such
b)		It is reflected
c)		It is scattered
d)		It is completely absorbed

5. Which of the following is most effective in coagulating a ferric byoxide sol?

a)		KCL
b)		KN $O_{3}$
c)		$K_{2} {SO}_{4}$
d)		$K_{3} [Fe ({CN)}_{6}]$

6. A colloidal system in which gas bubbles are dispersed by different methods differ because of

a)		Foam
b)		Sol
c)		Aerosol
d)		Emulsion

7. Which one of the following is not a colloid?

a)		Milk
b)		Blood
c)		Ice-cream
d)		urea solution

8. Which of the following is a hydrophobic sols?

a)		Protein sol
b)		Starch sol
c)		Gum sol
d)		Fe ${(OH)}_{3}$ sol

9. Which of the following colloidal solutions do not contain negatively charged colloidal particles?

a)		Fe ${(OH)}_{3}$ sol
b)		${As}_{2} S_{3}$ sol
c)		Blood
d)		Gold sol

10. On adding one ml solution of 10 $%$ NaCL to 10 ml gold sol in the presence of 0.25 gm of starch, the coagulation is just prevented. Starch has the gold number

a)		0.025
b)		0.25
c)		2.5
d)		250

11. Which one of the following substances gives a positively charged sol?

a)		Gold
b)		A metal sulphide
c)		Ferric hydroxide
d)		An acidic dye

12. Silver iodide is used for producing artificial rain because AgL

a)		Is easy to spray at high altitudes
b)		in insoluble in water
c)		is a cheap chemical
d)		has crystal structure similar to ice

13. In the preparation of AgL sol, excess of KL solution is added to AgN $O_{3}$ solution. The charge on the colloidal particles would be

a)		Positive
b)		Negative
c)		No charge
d)		Unpredictable

14. The average molecular mass of colloidal particles can be determined by study of

a)		Elevation in boiling point
b)		Osmotic pressure
c)		Tyndall effect
d)		Lowering of vapour pressure

15. Which of the following is an example of asociated colloid?

a)		Polyethylene sol
b)		Rubber sol
c)		PVC sol
d)		Soap sol

16. In which of the following respects the Lyophilic sols do not differ from Lyophobic sols?

a)		Stability
b)		Reversibility
c)		Particle size
d)		Behaviour towards dispersion medium

17. In coagulating the collodical solution of As2S3 which has the minimum coagulating value

a)		NaCL
b)		KCL
c)		BaCL2
d)		ALCL3

18. In a collodical state, size of particle ranges from

a)		1 to 10 $\overset{0}{A}$
b)		20 to 50 $\overset{0}{A}$
c)		10 to 1000 $\overset{0}{A}$
d)		1 to 280 $\overset{0}{A}$

19. Lyophilic sols have .......between disperse phase and dispersion medium

a)		strong attractive interaction
b)		Little attractive interaction
c)		Repulsive interaction
d)		None of these

20. Tyndall effect in colloidal solution is due to

a)		Scattering of light
b)		Reflection of light
c)		Absorption of light
d)		Presence of electrically charged particles

21. Which of the following statements is true for chemisorption?

a)		It is reversible in nature
b)		It is not specific in nature
c)		It exists in the form of monomolecular layer
d)		It occurs at low temperature

22. Which of the following is not true for physisorption?

a)		It is reversible
b)		It occurs in the form of multimolecular layers
c)		It needs activation energy
d)		It increases with increase in pressure

23. At CMC the surfactant molecules

a)		decompose
b)		become completely soluble
c)		associate
d)		dissociate

24. Detergent action of soups is due to

a)		Coagulation
b)		Emulsification properties
c)		Ionisation
d)		High molecular mass

25. Smoke is an example of

a)		Gas dispersed in liquid
b)		Gas dispersed in solid
c)		Solid dispersed in gas
d)		none of these

26. In the preparation of Agl sol, excess KI solution is added to AgN $O_{3}$ solution. The charge on the colloidal particles would be

a)		Positive
b)		Negative
c)		No charge
d)		unpredictable

27. Which of the following is less than zero during absorption?

a)		$Δ G$
b)		$Δ S$
c)		$Δ H$
d)		All of the above

28. Which of the following can form colloidal solution with water?

a)		Nacl
b)		Glucose
c)		Starch
d)		Barium nitrate

29. Which one of the following statements is not true?

a)		Milk is an example of an emulsion
b)		Boot-polish is an example of gel
c)		clouds are an example of liquid aerosol
d)		cheese is an example of solid sol

30. The size of the colloidal particles ranges between

a)		$10^{- 2} to 10^{- 3} cm$
b)		$10^{- 3} to 10^{- 5} cm$
c)		$10^{- 5} to 10^{- 7} cm$
d)		$10^{- 7} to 10^{- 9} cm$

31. A colloidal system in which gas bubbles are dispersed in liquid is known as

a)		Foam
b)		Sol
c)		Aerosol
d)		Emulsion

32. A negatively charged suspension of clay in water will need for precipitation the minimum amount of

a)		Aluminimum Chloride
b)		Potassium sulphate
c)		Sodium hydroxide
d)		Hydrochloric acid

33. Which one of the following will have the highest coagulating power for Fe ${(OH)}_{3}$ Sol

a)		P $O_{4}^{3 -}$
b)		S $O_{4}^{2 -}$
c)		A $l^{3 +}$
d)		N $a^{+}$

34. For adsorption of a gas on a solid adsorbent which of the following is positive?

a)		$Δ H$
b)		$Δ S$
c)		both a and b
d)		none of these

35. For Physisorption, heat of adsorption is generally in the range

a)		20-40KJ
b)		40-60KJ
c)		100-150KJ
d)		300-400KJ

36. The gold number of A,B,C and D are 0.04, 0.002, 10 and 25 respectively. Protective power of A,B and D are in the order:

a)		A > B > C > D
b)		B > A > C > D
c)		D > C > B > A
d)		C > A > B > D

37. Four different collids have the following gold number.Which one has its most effective action?

a)		10
b)		30
c)		20
d)		40

38. Flocculation value is expressed in terms of

a)		millimoles of electrolyte per litre of solution
b)		moles of electrolyte per litre of solution
c)		grams of electrolyte per litre of solution
d)		millimoles of electrolyte per millilitre of solution

39. Which adsorption does not take place at very low temperature?

a)		Physisorption
b)		Chemisorption
c)		Both (a) and (b)
d)		None of these

40. Surface tension of lyophilic sols is

a)		Lower than water
b)		More than water
c)		Equal to water
d)		None of these

41. Point out the false statement :

a)		Colloidal sols are homogeneous
b)		Colloids carry +ve or -ve charge
c)		Colloids show Tyndall effect
d)		The size range of colloidal particles is 10 - 1000 A

42. The colloidal sols are not purified by

a)		Peptisation
b)		Electro dialysis
c)		Dialysis
d)		Ultra centrifugation

43. For adsorption of a gas on solid adsorbent

a)		$Δ H$ is positive
b)		$Δ S$ is positive
c)		$Δ G$ is negative
d)		$Δ E$ is positive

44. Which of the following statements are true?

a)		Soap solution contains ionic micelles as the colloidal particles
b)		A water in oil emulsion easily spreads over surface of water
c)		Chemisorption is non-specific
d)		Chemisorption occurs in the form of multimolecular layers

45. The lyophilic colloid among the following is

a)		Blood
b)		Gold sol
c)		Fe(OH $)_{3}$ sol
d)		Starch

46. When a river enters the sea, a delta is formed. Formulation of delta is due to

a)		Peptization
b)		Coagulation
c)		Emulsification
d)		Dialysis

47. In which of the following respects the lyophilic sols do not differ from lyophobic sols?

a)		Stability
b)		Reversibility
c)		Particle size
d)		Behaviour towards dispersion medium

48. Protecting power of a lyophilic sol is expressed in terms of

a)		Coagulation value
b)		Gold number
c)		Both (a) and (b)
d)		None of these

49. Which of the following electrolytes will have maximum flocculation value for
Fe(OH $)_{3}$ sol?

a)		NaCl
b)		${Na}_{2} S$
c)		( ${NH}_{4}$ $)_{3} {PO}_{4}$
d)		$K_{2} {SO}_{4}$

50. A colloidal solution of a solid as dispersed phase and liquid as dispersion medium is known as

a)		Gel
b)		Sol
c)		Solid foam
d)		Emulsion