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
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