Surface Chemistry Test

TIME LEFT -

Question 1
4 / -1

The size of colloidal particles ranges between

A
10^-7 - 10^-9cm

B
10^-9 - 10^-11 cm

C
10^-5 - 10^-7 cm

D
10^-2 - 10^-3 cm

Question 2
4 / -1

Which of the following will not form a colloidal system?

A
Solid-gas

B
Liquid-gas

C
Gas-gas

D
Gas-liquid

Question 3
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Fog is an example of colloidal system of

A
Liuid in gas

B
Gas in liquid

C
Solid in gas

D
Gas in solid

Question 4
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A colloidal system in which liquid is dispersed phase and solid is dispersion medium is classified as

A
Gel

B
Sol

C
Emulsion

D
Aerosol

Question 5
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Which of the following examples is correctly matched?

A
Butter-gel

B
Smoke-emulsion

C
Paint-foam

D
Milk-aerosol

Question 6
4 / -1

Mark the incorrect combination out of the following examples of colloidal solutions.

A
a

B
b

C
c

D
d

Question 7
4 / -1

Lyophilic sols are also called reversible colloids because

A
They can be reformed by mixing residue (dispersed phase) in dispersion medium even after drying

B
They can be easily precipitated from the colloidal system

C
Once formed, the dispersion medium and dispersed phase cannot be separated

D
Special reversible reactions are used to prepare them

Question 8
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Which of the following factors contribute towards higher stability of lyophilic colloid?

A
Charge on their particles

B
Attractive forces between particles

C
Small size of their particles

D
High solvation due to a layer of dispersion medium

Question 9
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A lyophobic colloid cannot be formed by

A
Mixing dispersed phase and dispersion medium

B
Chemical reactions like hydrolysis

C
Exchange of solvent

D
Peptisation

Question 10
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Which of the following is not the correct difference between lyophobic and lyophillic sols?

A
a

B
b

C
c

D
d

Question 11
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Which of the following is not correctly matched?

A
Gelatain - Lyophilic colloid

B
Gold sol - Lyophilic colloid

C
Arsenious sulphide - Lyophobic colloid

D
Ferric hydroxide - Lyophobic colloid

Question 12
4 / -1

Substances which behave as normal electrolytes in solution at low concentration and exhibit colloidal properties at higher concentration are called

A
Lyophilic colloids

B
Lyophobic colloids

C
Macromolecular colloids

D
Associated colloids

Question 13
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In these colloids, a large number of small atoms or smaller molecules of a substance aggregate to form colloidal particles having size in colloidal range. These colloids are known as

A
Multimolecular colloids

B
Macromolecular colloids

C
Associated colloids

D
Lyophilic colloids

Question 14
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The substances which behave as colloidal solutions at higher concentration are called

A
Associated colloids

B
Multimolecular colloids

C
Macromolecuiar colloids

D
Protective colloids

Question 15
4 / -1

The formation of micelles takes place only above

A
Critical temperature

B
Kraft temperature

C
Inversion temperature

D
Absolute temperature

Question 16
4 / -1

The critical micelle concentration (CMC) is defined as

A
The concentration at which micellization starts

B
The concentration at which micelle start behaving like an electrolyte

C
The concentration at which dispersed phase is separated from dispersion medium

D
The concentration at which a colloid is converted to suspension

Question 17
4 / -1

At CMC (critical micelle concentration) the surface molecules:

A
Dissociate

B
Associate

C
Become bigger in size due to adsorption

D
Become smaller in size due to decomposition

Question 18
4 / -1

In the given figure label the parts.

A
A - Hydrophilic tail, B - hydrophobic head

B
A - Hydrophobic tail, B - hydrophobic head

C
A - Hydrophobic tail, B - hydrophilic head

D
A - Hydrophilic tail, B - hydrophilic head

Question 19
4 / -1

Soap mixed with water below critical micelle concentration behaves as

A
Associated colloid

B
Macromolecular colloid

C
Normal electrolytic solution

D
Multimolecular colloid

Question 20
4 / -1

White of an egg whipped with water acts as

A
Macromolecular colloid

B
Associated colloid

C
Molecular colloid

D
Normal electrolytic solution

Question 21
4 / -1

Colloidal solutions of metals like gold can be prepared when their salt solutions react with certain substances like SnCl₂, formaldehyde, phenyl hydrazine, etc.
2AuCl₃ + 3SnCl₂ → 3SnCl₄ + 2Au_sol
The above method is an example of

A
Reduction method

B
Oxidation method

C
Hydrolysis method

D
Double decomposition method

Question 22
4 / -1

In Bredigs arc method an electric arc is struck between the metal electrodes under the surface of water containing some stabilizing agent. The process involves

A
Mechanical dispersion

B
Condensation

C
Both dispersion and condensation

D
Ultrasonic dispersion

Question 23
4 / -1

When a small quantity of FeCl₃ solution is added to the fresh precipitate of Fe(OH)₃, a colloidal sol is obtained. The process through which this sol is formed is known as

A
Exchange of solvent

B
Chemical double decomposition

C
Peptization

D
Electrophoresis

Question 24
4 / -1

Which of the processes is being shown in the figure?

A
Electrodialysis

B
Dialysis

C
Electroosmosis

D
Electrophoresis

Question 25
4 / -1

Which of the following is not a method of removing impurities from a colloidal sol?

A
Electrodialysis

B
Ultrafiltration

C
Ultra centrifugation

D
Distillation

Question 26
4 / -1

Tyndall effect is observed only when
(i) the diameter of the dispersed particles is not much smaller than the wavelength of the light used.
(ii) the refractive indices of dispersed phase and dispersion medium differ greatly in magnitude.
(iii) the size of the particles is generally between 10^-11 and 10^-9 m in diameter.
(iv) the dispersed phase and dispersion medium can be seen separately in the system.

A
(i) and (iii)

B
(i) and (iv)

C
(ii) and (iii)

D
(i) and (ii)

Question 27
4 / -1

When a colloidal solution is viewed from the direction at right angles of light beam, the path of the beam is illuminated due to scattering of light In the figure (A) and (B) are

A
A - Tyndall cone, B - Scattered light

B
A-Scattered light, B-Tyndall cone

C
A - Tyndall cone, B - Blind spot

D
A - Tyndall effect, B - Tyndall cone

Question 28
4 / -1

Tyndall effect is not observed in

A
Smoke

B
Amulsions

C
Sugar solution

D
Gold sol

Question 29
4 / -1

Which of the following systems will show Tyndall effect?

A
Aqueous solution of sodium chloride

B
Aqueous solution of aluminium hydroxide

C
Aqueous solution of glucose

D
Aqueous solution of urea

Question 30
4 / -1

The cause of Brownian movement which is not shown by true solutions or suspensions is due to

A
Unbalanced bombardment of partices by molecules of the dispersion medium

B
Attractive forces between dispersed phase and dispersion medium

C
Larger size of the particles due to which they keep colliding and setting down

D
Conversion currents formed in the sol

Question 31
4 / -1

Why is ferric hydroxide colloid positively charged when prepared by adding ferric chloride to hot water?

A
Due to precipitation of ferric hydroxide there is an excess of Fe³⁺ ions

B
Due to preferential adsorption of Fe³⁺ ions by the sol of Fe(OH)₃

C
Due to absence of any negatively charged ion

D
Due to adsorption of OH^- and Cl^- ions, the remaining sol has only Fe³⁺ ions

Question 32
4 / -1

When an excess of a very dilute aqueous solution of KI is added to a very diute aqueous solution of silver nitrate, the colloidal particles of silver iodide are associated with which of the following Helmholtz double layer?

A
AgI : Ag⁺ : NO⁻₃

B
AgI : K⁺ : NO⁻₃

C
AgI : NO⁻₃ : Ag⁺

D
AgI : I⁻ : K⁺

Question 33
4 / -1

The combination of two layers of opposite charges around the colloidal particle is called Helmholtz electrical double layer. The potential difference between the fixed layer and the diffused layer of opposite charge is called

A
Electrode potential

B
Zeta potential

C
Adsorption potential

D
Diffused potential

Question 34
4 / -1

Which of the following is not an explanation for the origin of charge on the colloidal particles?

A
Due to frictional electrification

B
Due to dissociation of surface molecules

C
Due to electrophoresis

D
Due to selective adsorption of ions

Question 35
4 / -1

Movement of dispersion medium under the influence of electric field is known as

A
Electrodialysis

B
Electrophoresis

C
Eletroosmosis

D
Cataphoresis

Question 36
4 / -1

Why is alum added to water containing suspended impurities?

A
To make a colloidal solution

B
To coagulate the suspended impurities

C
To remove impurities of calcium and magnesium

D
To protect the colloidal solution from getting precipitated

Question 37
4 / -1

Mixing of positively charged colloidal solution with negatively charged colloidal solution brings _____. The decreasing order of coagulating power of Na⁺, Ba²⁺ and AI³⁺ for negatively charged colloidal solution is _____.

A
Mutual coagulation, Na⁺ > Ba²⁺ > AI³⁺

B
Mutual coagulation, Al³⁺ > Ba²⁺ > Na⁺

C
Coagulation, Na⁺, > Ba²⁺ > Al³⁺

D
Peptization, Al³⁺ > Ba²⁺ > Na⁺

Question 38
4 / -1

Which of the following acts as the best coagulating agent for ferric hydroxide sol?

A
Potassium ferrocyanide

B
Potassium chloride

C
Potassium oxalate

D
Aluminium chloride

Question 39
4 / -1

Fe(OH)₃ sol can be more easily coagulated by Na₃PO₄ in comparison to KCl because

A
Mass of Na₃PO₄ is more than KCl hence it is more effective the KCl

B
Phosphate ion (PO^3-₄) has higher negative charge than Cl^- ion hence are more effective for coagulation

C
KCl is more soluble than Na₃PO₄hence less effective for coagulation

D
Na⁺ ions are more effective than K⁺ ions for coagulation

Question 40
4 / -1

Which out of the following electrolyte solutions having the same concentration will be most effective in causing the coagulation of arsenic sulphide sol?

A
KCl

B
MgCl₂

C
AlCl₃

D
Na₃PO₄