Adsorption and Colloids

Multiple choice Questions:-

1) The change in concentration in the interfacial layers

between two phases of a system by surface forces is

called

a) Absorption b) Absorption

c) Sorption

d) Occlusion

Ans: (a)

a) Absorption

2) The extent of adsorption of a gas on a solid depend on

a) Nature of gas

b) Pressure of gas

c) Temperature of the system

d) All the correct

Ans: (d)

d) All the correct

3) Which of the following gases is adsored by charcoal?

a) H2

b) N2

c) NH3

d) CO2

Ans: (c) NH3 is easily liquifiable and highly water soluble gas.

c) NH3

4) Which is readily adsorbed by activated charcoal?

a) Cl2

b) CO2

c) H2

d) SO2

Ans: (b) CO2 is preferably adsorbed by charcoal.

b) CO2

5) The process of adsorption must be

a) Endoergic

b) Endothermic

c) Exothermic

d) None

Ans: (c)

c) Exothermic

6) Charcoal adsorb not only gases but also acts as

a) Reducing agent

b) Oxidising agent

c) Dehydrating agent

d) All

Ans: (a)

a) Reducing agent

7) Adsorption is accompanied by

a) Increase in enthalpy of the system

b) Decrease in enthalpy of the system

c) Decrease in temperature

d) All the correct

Ans: (b) Enthalpy change of adsorption is negative as adsorption is exothermic process

b) Decrease in enthalpy of the system

8) Which of the following substances adsorb hydrogen gas

most strongly?

a) Silica gel

b) Fe powder

c) Platinum black

d) Activated carbon

Ans: (c)

c) Platinum black

9) The phenomenon in which adsorption and absorption

takes place simultaneously is called

a) Sorption

b) Adsorption

c) Desorption

d) Deposition

Ans: (a)

a) Sorption

10) The coloring matter which gets adsorbed on activated

charcoal is called

a) Adsorbate

b) Adsorbent

c) Adsorbent

d) Adsorber

Ans: (a)

a) Adsorbate

11) Colloids are good adsorbents due to

a) their small surface area per unit mass.

b) their large dimensions.

c) their colligative properties.

d) their large surface area per unit mass.

Ans: (d)

d) their large surface area per unit mass.

12) The organic solvent that is used in chromatographic

separation is termed as

a) organosol

b) solvent

c) elutent

d) wash solution

Ans: (c)

c) elutent

13) The equilibrium attained in case of physical adsorption

is

a) static

b) dynamic

c) slow

d) all these

Ans: (b)

b) dynamic

14) The process of removal of an adsorbed substance from

the surface of a solid is known as

a) adsorption

b) sorption

c) desorption

d) all of these

Ans: (c)

c) desorption

15) The substance which act as adsorbent are

a) metals

b) colloids

c) silica gel

d) all these

Ans: (d)

d) all these

16) Increase in concentration of adsorbate at the surface of

a substance as compaired to bulk is called

a) negative adsorption

b) positive adsorption

c) desorption

d) sorption

Ans: (b)

b) positive adsorption

17) The curve indicating the variation of adsorption with

temperature at constant pressure is known as

a) adsorption isotherm

b) adsorption isobar

c) adsorption isotherm

d) adsorption isobar

Ans: (b)

b) adsorption isobar

18) Heat evolved per mole during chemisorption is in the

order of

a) 10 to 100 KJ

b) 40 to 400 KJ

c) 10 to 40 KJ

d) 1 to 10 KJ

Ans: (b)

b) 40 to 400 KJ

19) The heat evolved during adsorption in known as

a) heat of sorption

b) heat of desorption

c) heat of absorption

d) none of these

Ans: (d) In fact, heat of adsorption

d) none of these

20) Which of the following is correct is case of

Vander Waal’s adsortions?

a) high temperature and high pressure

b) low temperature and high pressure

c) high temperature and low pressure

d) low temperature and low pressure

Ans: (b)

b) Low temperature and high pressure

21) Which of the following adsorption takes place at high

temperature?

a) physical adsorption

b) chemical adsorption

c) Vander Waal’s adsorption

d) none of these

Ans: (b)

b) chemical adsortpion

22) Which of the following is true regarding chemisorption?

a) it is highly specific in nature

b) it is reversible in nature

c) it usually occurs at low temperature

d) it involves Vander Waal’s forces

Ans : (a)

a) It is highly specific in nature

23) Which of the following forms mono molecular layer of

adsorbate on the surface of adsorbent?

a) chemisorption

b) chemical adsorption

c) valency adsorption

d) all are correct

Ans: (d)

d) all are correct

24) The extent of physisorption

a) decrease with rise in temperature

b) increases with rise in temperature

c) in independent of temperature

d) first increases and then decreases with rise in

temperature

Ans: (a)

a) decrease with rise in temperature

25) Which one of the following is a properly of physical

adsorption?

a) non specific nature

b) high specificity

c) irreversibility

d) none

Ans: (a)

a) non specific nature

26) One which is not applicable to chemisorption is

a) It is favoured by high temperature

b) Effect of pressure is given by Freundlich

adsorption

c) It involves formation of monomolecular layer of

adsorbate

d) There is formation of chemical bonds between

adsorbent and adsorbate

Ans: (b)

b) Effect of pressure is given by Freundlich

adsorption

27) Chemical adsorption is27) Chemical adsorption is

a) exothermic a) exothermic

b) irreversibleb) irreversible

c) favoured by high temperaturec) favoured by high temperature

d) all of thesed) all of these

Ans: (d)

d) all of these

28) Point out the correct statement

a) Freundlich equation is valid over a limited

range

of pressure.

b) The constants K and n vary with temp.

c) Freundlich adsorption equation is purely

empirical

formula

d) All of the above

Ans: (d)

d) All of the above

29) Which of the following substance are used for drying of

gases.

a) silica gel

b) alumina

c) both a and b

d) neither a nor b

Ans: (c)

c) both a and b

30) Which of the following acts as best adsorbent?

a) charcoal

b) activated charcoal

c) carbon black

d) activated coconut charcoal

Ans: (c)

c) carbon black

31) Water is demineralised by passing through

a) cationic exchange resins

b) anionic exchange resins

c) both a and b

d) none

Ans: (c)

c) both a and b

32) Adsorption indicators were first introduced by

a) Dewar

b) K. Fajan

c) Domain

d) Tschugaeff

Ans: (b)

b) K. Fajan

33) Some statements are given about adsorption as

(i) It is a surface phenomenon

(ii) It involves energy changes

(iii) It is an endothermic process

(iv) It depends upon temperature

Among the above, the correct statements are

a) only i and ii

b) i, ii and iii

c) ii, iii and iv

d) i, ii, and iv

Ans : (d)

d) i, ii and iv

34) i) Physisorption is very rapid (ii) Chemsorption is reversible iii) In Chemisorption multi molecular layer of adsorbate is formediv) In physisorption chemical identity of the adsorbate remains sameamong these the true statement (s) is / are

a) only i and ii b) only ii and iiic) only I d) only i and iv

Ans: (d)

d) only i and iv

35) Colloidal particles carry charge, can be shown by?

a) Tyndall effect

b) Cataphoresis

c) Brownian Movement

d) Dialysis

Ans: (b) In applied electric field, the colloidal particles move towards electrode of opposite charge

b) Cataphoresis

36) Milk is an example of?

a) Emulsion

b) Suspension

c) True solution

d) Gel

Ans: (a) Liquid, fat globules dispersed in water medium is

milk

a) Emulsion

37) Light scattering takes place in?

a) Electrolysis solutions

b) Colloidal solution

c) Electrodialysis

d) Electroplating

Ans: (b) Optical property, Tyndall effect

b) Colloidal solution

38) Which of the following electrolysis is least effective in

causing coagulation of ferric hydroxide sol?

a) KBr

b) K2SO4

c) K2CrO4

d)K4[Fe(CN6)]

Ans: (a) Ferric hydroxide has positive colloidal particles so

need negative ion of electrolyte for coagulation. Br- ion

minimum valency.

a) KBr

39) Which of the following forms a colloidal solution in

water?

a) NaCl

b) Glucose

c) Starch

d) Barium nitrate

Ans: (c)

c) Starch

40) Which of the following is not a colloidal solution of gas

in liquid?

a) Froath b) Foams with tiny bubbles

c) Mist d) Whipped cream

Ans: (c) Mist is liquid in gas system.

c) Mist

41) Dust storm is?

a) Dispersion of solid in gas

b) Dispersion of a gas in solid

c) Dispersion of solid in sold

d) Dispersion of a gas in liquid

Ans: (a)

a) Dispersion of solid in gas

42) Gelatin is mostly used in making ice cream in order to?

a) Prevent making a colloid.

b) To stabilise the colloid and prevent crystallisation.

c) To stabilise mixture

d) To enrich the aroma

Ans: (b) Gelatin is a protective colloid.

b) To stabilise the colloid and prevent crystallisation.

43) Movement of colloidal particle under the influence of

electric field is called?

a) Electrophoresis

b) Dialysis

c) Ionisation

d) Electrodialysis

Ans: (a)

a) Electrophoresis

44) A negatively charged suspension of clay in water will

need for precipitation the minimum amount of?

a) AlCl3

b) K2SO4

c) HCl

d) NaOH

Ans: Al3+ ion maximum valency i.e. 3. Therefore it has

maximum amount is sufficient for precipatation.

a) AlCl3

45) The stability of lyophillic colloids is due to?

a) Charge on their particles

b) Smaller size of their particles

c) Large size of their particles

d) A layer of medium of dispersion of their particles

Ans: (d) The particles of lyophillic colloids are surrounded by molecules of dispersion medium solvent i.e. they are solvated.

d) A layer of medium of dispersion of their particles

46) Colloidal solution in which the dispersed phase has

little affinity for the dispersion medium is called?

a) Emulsions

b) Lyophillic colloids

c) Lyophobic colloids

d) Hydrophillic colloids

Ans: (c) Lyophobic means solvent heating.

c) Lyophobic colloids

47) For Coagulation of As2S3 Which is most effective

a) Na3PO4

b) MgCl2

c) CaCl2

d) AlCl3

Ans: (d) As2S3 sol particles are negatively charged due to

adsorption of S2- ion. The Al3+ ion is opposite has more

valency.

d) AlCl3

48) An emulsifier is a substance which?

a) Homogenises the emulsion

b) Stabilizes the emulsion

c) Accelerates the dispersion of liquid in liquid.

d) Coagulates the emulsion.

Ans: (b) Emulsifier forms its layer around the droplets of

liquid dispersed and there by prevent their aggregation.

Thus imparts stability to the emulsion.

b) Stabilizes the emulsion

49) In coagulation of sol, the increasing coagulating power

of following cations will be in the order

a) K+>Ba++>Sn++++

b) Sn++++>Al+++>Ba++>K+

c) Al+++>Ba++>K+>Sn++++

d) Al+++>K+>Sn++++>Ba++

Ans: (b)

b) Sn++++>Al+++>Ba++>K+

50) Medicines in colloidal form are more effective because

a) They are more soluble in water

b) They are easily absorbed and assimilated

c) They kill the germs

d) They interact easily

Ans: (b)

b) They are easily absorbed and assimilated

51) Arsenious sulphlde sol is

a) Positive colloid

b) Negative colloid

c) Neutral colloid

d) None

Ans : (b)

b) Negative colloid

52) Sodium Stearate in water forms

a) True solution

b) Suspension

c) Colloidal solution

d) An emulsion

Ans: (c)

c) Colloidal solution

53) Which one among the following sols is hydrophobic?

a) Sulphur

b) Sugar

c) Gum

d) Gelatin

Ans: (a)

a) Sulphur

54) Which of the following is a hydrophilic colloid?

a) BaSo4 sol

b) As2S3 sol

c) Starch sol

d) Agl Sol

Ans: (c)

c) Starch sol

55) When the dispersion medium is alcohol, the colloidal

sol is known as

a) Hydrosol

b) Benzosol

c) Alcohol

d) Aquasol

Ans: (c)

c) Alcohol

56) Spontaneous liberation of liquid from a gel is called

a) Peptization

b) Weeping of gels

c) Both (a) and (b)

d) None of the above

Ans:- (b)

c) Both (a) and (b)

57) Emulsions of polyvinyl acetate are used in57) Emulsions of polyvinyl acetate are used in

a) Grayonsa) Grayons

b) Latex paintsb) Latex paints

c) Polishesc) Polishes

d) Fire worksd) Fire works

Ans: (b)

b) Latex paints

58) Water is demineralised by passing through58) Water is demineralised by passing through

a) Cataionic exchange resinsa) Cataionic exchange resins

b) Anionic exchange resinsb) Anionic exchange resins

c) Both ‘a’ and ‘b’c) Both ‘a’ and ‘b’

d) Noned) None

Ans : (c)

c) Both ‘a’ and ‘b’

59) Which of the following substances can be used for59) Which of the following substances can be used for

refining of petroleum and vegetable oils? refining of petroleum and vegetable oils?

a) Sodium aluminium silicatea) Sodium aluminium silicate

b) Permutit i.e. Zeolitesb) Permutit i.e. Zeolites

c) Fuller’s earth & Silica gelc) Fuller’s earth & Silica gel

d) Activated charcoald) Activated charcoal

Ans: (c)

c) Fuller’s earth & Silica gel

60) Gelatin is often used as an ingredient in the60) Gelatin is often used as an ingredient in the

manufacture of ice cream. The purpose of adding manufacture of ice cream. The purpose of adding

gelatin is gelatin is

a) To prevent formation of colloidal sol.a) To prevent formation of colloidal sol.

b) To stabilize the colloids & prevent crystal growthb) To stabilize the colloids & prevent crystal growth

c) To improve the flavourc) To improve the flavour

d) To increase the bulkd) To increase the bulk

Ans: (b)

b) To stabilize the colloids & prevent crystal growth

61) Ferric chloride is applied to stop bleeding cut, because:61) Ferric chloride is applied to stop bleeding cut, because:

a) Fea) Fe3+3+ ion coagulates blood, which is a negatively ion coagulates blood, which is a negatively

charged sol charged sol

b) Feb) Fe3+3+ ion coagulates blood, which is a positively ion coagulates blood, which is a positively

charged sol charged sol

c) l- coagulates blood, which is a positively chargedc) l- coagulates blood, which is a positively charged

sol sol

d) Cl- ion coagulates blood, which is a negativelyd) Cl- ion coagulates blood, which is a negatively

charged sol charged sol

Ans: (a)

a) Fe3+ ion coagulates blood, which is a negatively

charged sol

62) In preparation of colloidal solution by Bredig’s are62) In preparation of colloidal solution by Bredig’s are

method, traces of caustic alkali are added method, traces of caustic alkali are added

a) To make it homogenousa) To make it homogenous

b) To stabilize the solb) To stabilize the sol

c) As peptising agentc) As peptising agent

d) As coagulating agentd) As coagulating agent

Ans: (b)

b) To stabilize the sol

63) Preparation of ice cream is based on the principle of63) Preparation of ice cream is based on the principle of

a) Exchange of solventa) Exchange of solvent

b) Peptizationb) Peptization

c) Coagulationc) Coagulation

d) Excessive coolingd) Excessive cooling

Ans: (d)

d) Excessive cooling