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Colloid Chemistry Questions — True or False

Total questions: 130

Worksheet time: 1hrs 7mins

Name
Class
Date
1.

True or false: Molecular weight of polymers can be determined by the intrinsic viscosity.

a)

True

b)

False

2.

True or false: At the isoelectric point proteins tend to aggregate.

a)

True

b)

False

3.

True or false: A mixture of two phases is called a surface or an interface.

a)

True

b)

False

4.

True or false: Molecules can be separated based on their size with Isoelectric focusing.

a)

True

b)

False

5.

True or false: In case of chain reactions, the polymer molecules can be isolated during the reaction.

a)

True

b)

False

6.

True or false: Utilizing ionic polymerization, a narrower molecular weight distribution can be achieved.

a)

True

b)

False

7.

True or false: Amphiphilic molecules can be used as wetting agents or solubilizer.

a)

True

b)

False

8.

True or false: Morphology is the only important parameter in case of colloidal systems.

a)

True

b)

False

9.

True or false: The size limits of colloidal systems are the following: 1–10 000 nm.

a)

True

b)

False

10.

True or false: The viscosity of Newtonian fluids depends on shearing tension.

a)

True

b)

False

11.

True or false: Temperature and the characteristics of the emulgents are determining factors of the emulsion stability.

a)

True

b)

False

12.

True or false: Super-hydrophobic surface means the contact angle is smaller than 150 degree.

a)

True

b)

False

13.

True or false: For chemisorption, the energy is typically less than 50 kJ/mol.

a)

True

b)

False

14.

True or false: Tyndall effect means Rayleigh scattering on colloidal particles.

a)

True

b)

False

15.

True or false: The TWEEN and SPAN surface active molecules are anionic amphiphiles.

a)

True

b)

False

16.

True or false: Gibbs free energy of the system decreases during spontaneous changes at constant pressure and temperature ( ΔG<0\Delta G < 0 ).

a)

True

b)

False

17.

True or false: Size is not important in case of colloidal systems.

a)

True

b)

False

18.

True or false: Intermolecular forces have no effect on the degree of wettability.

a)

True

b)

False

19.

True or false: The Stokes–Einstein equation is not sensitive for the shape of the particle; it is valid for every kind of shapes.

a)

True

b)

False

20.

True or false: The Höppler viscometer operates on a rotating basis; it is a rotational viscometer.

a)

True

b)

False

21.

Lyophobic sols are a type of suspensions. Choose True or False.

a)

True

b)

False

22.

Association colloids are built up from surfactants. Choose True or False.

a)

True

b)

False

23.

Usually coagulation is non‑reversible, whereas flocculation can be reversed. Choose True or False.

a)

True

b)

False

24.

The packing parameter describes the molecular weight of an amphiphilic molecule. Choose True or False.

a)

True

b)

False

25.

The critical coagulation concentration is the salt concentration which causes slow aggregation. Choose True or False.

a)

True

b)

False

26.

In emulsions, the dispersed phase and the media are always liquid phases. Choose True or False.

a)

True

b)

False

27.

In differential centrifugal sedimentation used to calculate particle size, gravitational force is replaced by centrifugal acceleration. Choose True or False.

a)

True

b)

False

28.

Particle size is an important parameter in the calculation of HLB value. Choose True or False.

a)

True

b)

False

29.

Suspension can be prepared by either condensation or dispersion method. Choose True or False.

a)

True

b)

False

30.

DLVO theory combines the effects of Van der Waals attraction and electrostatic repulsion. Choose True or False.

a)

True

b)

False

31.

Foams are concentrated gas lyosols where the liquid phase thins into lamellae. Choose True or False.

a)

True

b)

False

32.

Adsorption is a chemically controlled distribution of charged species governed by the in situ developed electrified interface. Choose True or False.

a)

True

b)

False

33.

The surface tension of a solution decreases with increasing amount of surface‑active agent. Choose True or False.

a)

True

b)

False

34.

Association colloids are made of symmetrical molecules, the so‑called amphipathic molecules. Choose True or False.

a)

True

b)

False

35.

Surface‑active property of a surfactant means the surface tension of its solution decreases as the concentration of the surfactant increases. Choose True or False.

a)

True

b)

False

36.

The specific conduction decreases after reaching the CMC value. Choose True or False.

a)

True

b)

False

37.

In the Gouy–Chapman model we consider ions as point charges and account for thermal motion. Choose True or False.

a)

True

b)

False

38.

Association colloids are built up from macromolecules. Choose True or False.

a)

True

b)

False

39.

When using a Donnan pipette, the droplet number of tenside‑containing solution is determined in the oil phase. Choose True or False.

a)

True

b)

False

40.

A Donnan pipette is filled with an unknown tenside solution, then the pipette is immersed into sunflower oil, and finally the number of droplets formed in the oil is determined. Choose True or False.

a)

True

b)

False

41.

An Ostwald‑type viscometer is suitable for determining both absolute and relative viscosity. Choose True or False.

a)

True

b)

False

42.

Traube’s stalagmometer is suitable for the measurement of liquid–liquid interfacial tension. Choose True or False.

a)

True

b)

False

43.

Increasing concentration of a surface‑active agent decreases the surface tension and therefore decreases the number of droplets as well. Choose True or False.

a)

True

b)

False

44.

Surfactants can be used as suspending agents and wetting agents. Choose True or False.

a)

True

b)

False

45.

Gas lyosol: gas phase is dispersed in a liquid dispersion medium. Choose True or False.

a)

True

b)

False

46.

The viscoelastic property can be determined by oscillating rheological measurements. Choose True or False.

a)

True

b)

False

47.

Suspensions can not be used for oral dosage. Choose True or False.

a)

True

b)

False

48.

The LaMer model describes nucleation and growth of nano‑crystals as a function of reaction time and concentration of precursor atoms. Choose True or False.

a)

True

b)

False

49.

A boundary between two phases is called a surface of an interface. Choose True or False.

a)

True

b)

False

50.

The Donnan pipette can measure liquid–liquid surface tension. Choose True or False.

a)

True

b)

False

51.

The Stokes–Einstein equation is sensitive to particle shape and is valid only for spherical shapes. Choose True or False.

a)

True

b)

False

52.

If a narrow capillary tube is dipped into a liquid, the liquid level in the tube is independent of the tube diameter. Choose True or False.

a)

True

b)

False

53.

The packing parameter describes the surface tension of an amphiphilic molecule. Choose True or False.

a)

True

b)

False

54.

Physical gels turn liquid under elevated temperatures. Choose True or False.

a)

True

b)

False

55.

According to the Gouy–Chapman model, if the surface is immersed in a symmetric electrolyte and the surface potential is +35 mV and the Debye length (k⁻¹) is 9.6 nm, what is the potential at a distance of 20 nm from the surface?

a)

+25 mV

b)

+4.4 mV

c)

+280 mV

d)

0 mV

56.

According to the DLVO theory the interaction between two colloidal particles is…

a)

the sum of the Born-potential, the van der Waals and electrostatic potentials

b)

the sum of the electrostatic and van der Waals interactions

c)

is always repulsive at big separation and attractive at small separation distances

57.

According to the Stokes-equation how long would it take for all particles with 200 mm radius to sediment out from a liquid column with a height of 10 cm under normal gravity (g = 9.8 m/s²)? Density difference 1000 kg/m³, liquid viscosity 0.001 Pa·s.

a)

1.8 days

b)

13.3 days

c)

3.7 hours

d)

35.2 days

e)

19 hours

58.

What was the significance of the ultramicroscope invented by R. Zsigmondy?

a)

Giving extra information about the size distribution of particles

b)

First visualization of colloidal particles

c)

First iron sol preparation

d)

Preparation of the first drug delivery system

59.

The isoelectric point of gelatin can be determined with…

a)

Ostwald–Fenske type capillary viscometer, by measuring the flow time of the solutions

b)

Ostwald–Fenske type capillary viscometer, by counting the droplets

60.

The Schulze-Hardy rules state:

a)

the critical coagulation concentration (c.c.c.) depends inversely on the sixth power of the charge of the ions.

b)

the critical coagulation concentration (c.c.c.) depends inversely on the tenth power of the charge of the ions.

c)

the critical coagulation concentration (c.c.c.) depends linearly on the sixth power of the charge of the ions.

d)

the critical coagulation concentration (c.c.c.) depends linearly on the tenth power of the charge of the ions.

61.

The negligible factor in case of the thermodynamics of micelle formation is:

a)

tail-tail interaction

b)

head-head interaction

c)

water-water interaction

d)

surfactant-water interaction

62.

In case of capillary condensation

a)

The adsorption isotherm has a hysteresis

b)

Multilayer adsorption is not allowed

c)

The gas phase cannot condensate

d)

The pores of the solid phase are negligible

63.

Choose the correct statement

a)

the temperature dependence of the viscosity can be described by the Arrhenius equation

b)

the viscosity of most materials increases with increasing temperature

c)

temperature does not affect viscosity

d)

the viscosity can be calculated as follows: multiplication of shear stress and shear force

64.

Pick the wrong answer for the following: methods for particle size analysis:

a)

Ostwald viscometer

b)

Differential centrifugal sedimentation

c)

Dynamic light scattering

d)

Nano-tracking analyzer

65.

The unit of relative viscosity is:

a)

it has no unit

b)

Pa*s

c)

mL/g

d)

g/mL

66.

Based on the DLVO theory the irreversible aggregation of suspensions:

a)

it happens when the system reaches the first maximum on the potential bridge

b)

when the system reached the secondary minimum

c)

when the system reaches the primary minimum

d)

when the system cannot jump the energy barrier

67.

The shape of the micelles is:

a)

independent of the concentration

b)

dependent on the packing parameter

c)

independent of the temperature

68.

The relation between intrinsic viscosity and relative molecular weight is given by:

a)

Kuhn-Mark-Houwink equation

b)

Fick equation

c)

Hagen-Poiseuille equation

69.

The critical micelle concentration depends on

a)

pressure and humidity

b)

temperature

70.

The roughness of the surface is important in which topic?

a)

surface tension

b)

contact angle

c)

specific surface area

d)

HLB value

71.

The unit of surface tension

a)

cm^2/A

b)

m/N^2

c)

N/m

d)

N/m^2

72.

The blue color of the sky is caused by...

a)

Rayleigh scattering

b)

Mie scattering

c)

Non-elective scattering

73.

What is the definition of coverage?

a)

chemical structure of the adsorbate does not change, but the number of degrees of freedom of its motion decreases.

b)

number of surface sites occupied by the adsorptive divided by the total number of surface sites.

c)

the amount of adsorbed gas as a function of the equilibrium gas pressure.

d)

molecular chemically or physically bound onto the solid surface from the gas or liquid phase.

74.

Upon increasing temperature, viscosity...

a)

increases

b)

first increases then decreases

c)

does not change

d)

decreases

75.

The unit of relative viscosity:

a)

g/ml

b)

Pa*s

c)

does not have unit

76.

At isoelectric point, the molecular reaches a state in which:

a)

the number of the positive and that of the negative charges are equal to each other and therefore the overall charge of the molecule is zero.

b)

the molecule doesn't have any charged functional groups.

c)

none of them is true.

d)

the viscosity of its solution has a minimum value.

77.

What is the assumption in case of Langmuir isotherm?

a)

multilayer adsorption

b)

equilibrium between the adroption and desorption

c)

monolayer adsorption

d)

heterogeneous surface

78.

Over the CMC:

a)

neither the micelle, nor the monomer concentration are not changing

b)

the micelle concentration is not changing

c)

the tenside concentration in the boundary layer (monomer) is not changing

d)

the solvent concentration is not changing

79.

How the viscosity depends on the volume of the sample in the case of Ostwald type viscometry?

a)

inversely proportional to the square of the volume

b)

independent

c)

linearly proportional

d)

inversely proportional

80.

Choose the correct statement in connection with the aqueous tenzide containing systems

a)

over the CMC, the surface tension is not decreasing any further.

b)

over the CMC, the surface tension starts to decrease significantly.

c)

when the tenside concentration is below the CMC, the phase-boundary surface tension is constant.

d)

to the CMC value, the maximum of phase-boundary surface tension can be ordered.

81.

The line of surface tension depending on the natural base logarithm of tenside concentration consists of two different running lines. What can be found in the point of intersection?

a)

CMC

b)

pH

c)

Isoelectric point

d)

pOH

82.

Before reaching the CMC:

a)

contains only a minimal quantity of micelles

b)

the surface tension does not change with increasing concentration of the surface active agent

c)

the surface tension is lower than after the CMC

d)

the tenside containing system is a colloidal solution

83.

What is the difference in the operation theory of the Traube stalagmometer and the Donnan pipette?

a)

The Traube stalagmometer measures liquid/gas phase-boundary surface tension, the Donnan pipette measures liquid/liquid phase-boundary surface tension

b)

The Traube stalagmometer measures flow rate, the Donnan pipette measures drop numbers

c)

The Donnan pipette is used in cases of non-ionic tensides, the Traube stalagmometer is used in the instance of ionic tensides

d)

The Donnan pipette, unlike the Traube stalagmometer, is incapable of measuring tenside solutions

84.

Choose the correct answer: Over the CMC, which characteristics of the solution is not changing

a)

Micelle concentration

b)

Surface tension

c)

Monomer tenside concentration

d)

Droplet size

85.

The size exclusion chromatography separates polymers based on:

a)

Size

b)

Molecular weight

c)

Flow rate

d)

Functional groups

86.

For cationic surfactants:

a)

The hydrophobic part has a positive charge

b)

The surfactant portion has a positive charge

c)

The surfactant portion has both charges

d)

The surfactant portion has any charge

87.

The zeta potential can be determined using the following theory:

a)

Helmholtz model

b)

Gouy-Chapman model

c)

Stern model

d)

Stokes model

88.

The surface tension:

a)

Goes down with rising temperature

b)

Rises with rising temperature

c)

Goes down with dropping temperature

d)

Is independent of the temperature

89.

Select the categories of colloidal systems.

a)

Macromolecular systems

b)

Disperse system

c)

Association colloids

d)

Homogeneous systems

90.

What environmental parameters do have an effect on the formation of polyelectrolyte complexes?

a)

Temperature

b)

pH

c)

Reaction time

d)

Charge density

91.

What are the characteristics of rubber elasticity?

a)

Delayed elastic deformation

b)

Glass state

c)

Segment motion

d)

Irreversible

92.

Which sentences are correct for the lyophobic colloids?

a)

Smog is a lyophobic colloidal system.

b)

Fog is a lyophobic colloidal system.

c)

Fog and association colloids are lyophobic colloids.

d)

Only association colloids are lyophobic.

93.

A colloidal system from lyosol state can reach lyogel state by

a)

heating

b)

removal of the solvent

c)

cooling

d)

addition of solvent

94.

Choose the correct statement(s) for the HLB value.

a)

The more dominant the hydrophobic part of the surfactant, the higher the HLB becomes.

b)

HLB is additive in case of complex emulgents.

c)

Can be calculated from hydration heat and mass fraction/percentage of etoxy groups.

d)
95.

Pick the correct sentences.

a)

The smaller the particle the higher the dispersity.

b)

Dispersity value is inversely proportional to the particle diameter.

c)

Dispersity value describes mono-disperse systems.

d)

If the particle is spherical the diameter is a good indicator for predicting dispersity.

96.

How can we interpret the size distribution of particles?

a)

With integral distribution curve.

b)

With the presentation of zeta potential.

c)

With differential distribution curve.

d)

None of the other three options is appropriate to show the size distribution of the particles.

97.

Choose the right statements about specific conductivity.

a)

With conductivity values measured with a conductometer and knowing the so-called cell constant, we can calculate the specific conductivity values of the solutions.

b)

The specific conductivity has a minimum value at CMC.

c)

The unit of specific conductivity: S/m.

d)

The unit of specific conductivity: Sm2/mol

98.

Choose the properties from the list below which change when the protein reaches the isoelectric point.

a)

molecular weight

b)

stability

c)

viscosity of the solution

d)

swelling ratio

99.

The wettability depends on

a)

The surface tension of the triple interface formed between solid, liquid, and gas.

b)

The Freundlich isotherm.

c)

The adsorption and desorption equilibria.

d)

Adhesive and cohesive forces between the solid and the liquid phases.

100.

Choose the non-ionic surfactant(s).

a)

Soaps

b)

Glycerol monostearate

c)

Benzalkonium chloridum

d)

Tween

101.

What is the assumption in case of Langmuir isotherm?

a)

Equilibrium between adsorption and desorption

b)

Multilayer adsorption

c)

Heterogeneous surface

d)

Monolayer adsorption

102.

Electrostatic repulsion depends on

a)

The size of the particle

b)

The thickness of the steric double layer

c)

The Stern potential

d)

The thickness of the electric double layer

103.

How can we destabilize a foam?

a)

In time the spherical foams (due to the decreasing liquid content) turn into polyhedral foams.

b)

In time the spherical foams become bigger and bigger.

c)

With the coalescence of bubbles.

d)

With the fusion of the water molecules.

104.

Which parameters of the adsorbent influence the amount of adsorbed gas?

a)

Quality of the material.

b)

Porosity.

c)

Density.

d)

Temperature.

105.

Choose the right units of viscosity.

a)

Pa*s

b)

cP

c)

Pa

d)

N∗m−2N*m^{-2}

106.

It is true for surface free energy

a)

Is the work required to increase the surface area of a liquid by unit area.

b)

The unit of the surface free energy is: mJ/m^2.

c)

The surface free energy numerically equal and dimensionally equivalent with surface tension.

d)

The surface free energy and the surface tension have the same unit (mN/m).

107.

The Traube stalagmometer

a)

Is used for the determination of relative surface tension

b)

It can be only used if we have a standard solution (with a known surface tension, like water)

c)

Suitable for determining the oil/water surface tension

d)

The geometry of the instrument does not effect the droplet number

108.

It is true for the micelle formation

a)

we can form micelles just if we have high enough surface tension

b)

appears above the concentration of the homogenous solution

c)

depend on the concentration of the tenside

d)

we can form micelles just if we have colloidal solution (concentration reaches the CMC)

109.

Donnan pipette

a)

Before the usage a calibration is necessary

b)

we can determine the surface tension between any kind of liquids using Donnan pipette

c)

The increasing number of droplet is inversely proportional with the measured decreasing surface tension

d)

We count the droplets of the material with lower density in the material with higher density

110.

To determine the surface tension with a Donnan pipette the following information is necessary:

a)

Radius of the capillary (where the droplet is forming)

b)

The volume of the droplets

c)

Concentration of the solvent

d)

Viscosity of the material

111.

It is valid for the Traube stalagmometry:

a)

It can be used to determine the relative surface tension at liquid/gas interface

b)

It can be used to determine the liquid/liquid surface tension

c)

The stalagmometer was filled with sunflower oil

d)

The stalagmometer was filled with the tenside solution

112.

It is true for the measurement with an Ostwald-Fenske-type viscometer, that

a)

the number of drops of a given volume of examined liquid is measured

b)

the value of the relative viscosity of the examined liquid can be determined based on the measured value

c)

it is suitable for determining the interfacial tension

d)

the efflux time of a given volume of the examined liquid is measured

113.

The Donnan pipette can be used for:

a)

Determination of surface tension

b)

Determination of CMC

c)

Determination of the molecular mass

d)

Determination of the area of 1 molecule

114.

In case of flocculated suspension, the mixture can be redispersed with low energy input.

a)

True

b)

False

115.

viscosity can be calculated as follows: shear stress divided by the shear rate

a)

true

b)

false

116.

the degree of dispersion of suspensions is reduced if the constituent solid particles maintain their independence of motion and no aggregation occurs

a)

true

b)

false

117.

DLS can measure both the zeta potential and the size of the solid nanoparticles

a)

true

b)

false

118.

only ionic surfactants can be used to stabilize foams

a)

true

b)

false

119.

foam formation can be unfavorable in certain pharmaceutical technological processes

a)

true

b)

false

120.

In the case of pharmaceutical suspensions, the administered dose is significantly influenced by the solubility of the active substance

a)

true

b)

false

121.

by mixing different emulsifiers, the HLB value can be modified to ... the formulation purpose

a)

true

b)

false

122.

the packing parameter describes the surface tension of an amphipathic molecule

a)

true

b)

false

123.

mark the most thermodynamically stable dispersion

a)

macrosuspension

b)

macroemulsion

c)

microemulsion

d)

nanoemulsion

124.

which of the following advantages make the microemulsion-based systems a good therapeutic option?

a)

small droplet size

b)

increased bioavailability

c)

short term stability

d)

possibility to formulate in hard capsules

125.

the surface tension depends on the:

a)

temperature

b)

concentration of a component in the solution

c)

gibbs coefficient

d)

dupre constant

126.

which properties of a polymer solution of unknown molecular weight are required to determine the intrinsic viscosity?

a)

reduced viscosity

b)

concentration

c)

pH

d)

degree of light scattering

127.

characteristic of the amphipathic molecule

a)

the hydrophilic moiety is usually a hydrocarbon chain

b)

if the hydrophilic portion is large enough, the molecule is soluble in water

c)

if the hydrophilic part dominates, the apolar part is enriched at the water-air interface furthest from the water

d)

molecules that have both hydrophilic and hydrophobic moieties

128.

solubilization:

a)

forms a real solution

b)

distribution of water-insoluble / poorly soluble active ingredients in an aqueous medium

c)

transition between molecular dissolution and dispersion

d)

dissolving a gas in a liquid

129.

When CMC is reached, upon further addition of surfactant, which parameters increase further?

a)

surface tension

b)

osmotic pressure

c)

surfactant monomer concentration

d)

light scattering intensity

130.

it is true for the determination of the solubility of benzoic acid:

a)

the solubility capacity can be determined based on the slope of the line by plotted the concentration of benzoic acid as a function of the surfactant concentration

b)

the molar ratio of the neutralization reaction is 1:2 NaOH:benzoic acid

c)

the addition of non-ionic surfactant to the benzoic acid solution is not enhance the dissolved and solubilized benzoic acid concentration

d)

acid base type titration is used

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