Colloid and Interface Science: Online Quizzes and Learning Resources

Question 1

Which force is primarily responsible for the stability of lyophobic colloids?

Accepted Answer

Electrostatic repulsion

Answer

Van der Waals attraction

Answer

Brownian motion

Answer

Hydrogen bonding

Question 2

Which application of colloids utilizes their ability to scatter light?

Accepted Answer

Paint

Answer

Detergents

Answer

Food emulsions

Answer

Drug delivery

Question 3

What term describes the boundary region between two immiscible liquids?

Accepted Answer

Interface

Answer

Colloid

Answer

Emulsion

Answer

Micelle

Question 4

How do surfactants reduce the interfacial tension between liquids?

Accepted Answer

They form a monolayer at the interface

Answer

They increase the solubility of one liquid in the other

Answer

They decrease the surface area of the interface

Answer

They neutralize the electrostatic charges at the interface

Question 5

Which substance is an example of an emulsion?

Accepted Answer

Milk

Answer

Salt water

Answer

Air in water

Answer

Steel in water

Question 6

Which technique is commonly used to determine the size of colloidal particles?

Accepted Answer

Dynamic light scattering

Answer

Gel electrophoresis

Answer

Atomic force microscopy

Answer

Nuclear magnetic resonance

Question 7

Identify the characteristic that is NOT a property of colloids.

Accepted Answer

Homogeneous nature

Answer

Presence of a dispersed phase

Answer

Presence of a dispersion medium

Answer

Small particle size range

Question 8

In a colloidal dispersion, what is the role of a surfactant?

Accepted Answer

To decrease the surface tension of the particles and enhance particle stability

Answer

To increase the surface tension of the particles

Answer

To stabilize the particles against coagulation

Answer

To increase the viscosity of the dispersion

Question 9

What is the primary effect of increasing the concentration of a colloidal dispersion?

Accepted Answer

Increased viscosity

Answer

Increased particle size

Answer

Decreased particle size

Answer

Decreased stability

Question 10

Which property is NOT characteristic of interfaces?

Accepted Answer

Bulk diffusion

Answer

Surface tension

Answer

Adhesion

Answer

Capillary action

Question 11

Which property is distinctive to colloids?

Accepted Answer

Tyndall effect

Answer

High viscosity

Answer

Low surface tension

Answer

Brownian motion

Question 12

Which measure enhances the stability of colloids?

Accepted Answer

Adding electrolytes

Answer

Increasing temperature

Answer

Reducing particle size

Answer

Lowering pH

Question 13

When two immiscible liquids are in contact, which type of interface is formed?

Accepted Answer

Liquid-liquid

Answer

Solid-liquid

Answer

Liquid-gas

Answer

Gas-solid

Question 14

Surfactants play a crucial role in which process?

Accepted Answer

Emulsification

Answer

Flocculation

Answer

Coagulation

Answer

Precipitation

Question 15

Which example represents a hydrophilic colloid?

Accepted Answer

Starch

Answer

Gold nanoparticles

Answer

Silver chloride

Answer

Polystyrene

Question 16

The zeta potential of a colloidal particle primarily provides information about:

Accepted Answer

Surface charge

Answer

Particle size

Answer

Stability

Answer

Viscosity

Question 17

The Gibbs adsorption equation primarily describes:

Accepted Answer

The variation in surface tension with concentration

Answer

Adsorption isotherm

Answer

Effect of temperature on adsorption

Answer

Rate of adsorption

Question 18

Which of the following is **not** an advantage of using colloids as drug delivery systems?

Accepted Answer

Increased immunogenicity

Answer

Increased drug bioavailability

Answer

Sustained drug release

Answer

Reduced side effects

Question 19

What is the definition of interfacial energy?

Accepted Answer

The energy needed to separate two phases at their interface.

Answer

The energy stored in the bulk phases of a system.

Answer

A positive quantity that always opposes the formation of interfaces.

Answer

A quantity that is independent of the surface area of the interface.

Question 20

Which of the following accurately describes a key characteristic of colloids?

Accepted Answer

Particles dispersed throughout a medium, remaining suspended without settling.

Answer

Absence of Brownian motion, resulting in static particle distribution.

Answer

Large particle size, visible to the naked eye.

Question 21

Which of the following is a common industrial application of colloids?

Accepted Answer

Paints, where pigments are dispersed in a liquid medium.

Answer

Fuel cells, utilizing electrochemical reactions for energy generation.

Answer

Semiconductors, relying on controlled conductivity of solid materials.

Answer

Nuclear reactors, primarily relying on nuclear reactions.

Question 22

Which of the following properties of interfaces is a direct measure of their resistance to deformation?

Accepted Answer

Surface tension, the force per unit length acting along the interface.

Answer

Conductivity, a measure of how easily electricity flows through the interface.

Answer

Viscosity, a measure of a fluid's resistance to flow.

Answer

Density, a measure of mass per unit volume.

Question 23

How do surfactants modify the properties of interfaces?

Accepted Answer

Surfactants reduce surface tension and stabilize emulsions by creating a barrier between immiscible liquids.

Answer

Surfactants increase surface tension and promote coalescence of dispersed phases.

Answer

Surfactants have no effect on interface properties, acting only as inert substances.

Question 24

Which of the following techniques is commonly used to measure the surface tension of liquids?

Accepted Answer

Pendant drop method, where the shape of a hanging drop is analyzed.

Answer

Gas chromatography, a method for separating and analyzing volatile compounds.

Answer

Polarography, a technique for studying electrochemical reactions.

Answer

Titration, a technique for determining the concentration of a substance.

Question 25

What is the significance of contact angle in wetting phenomena?

Accepted Answer

Contact angle determines whether a liquid will spread on a surface, influencing its wetting behavior.

Answer

Contact angle has no practical applications and is purely a theoretical concept.

Answer

Contact angle is only relevant for solid surfaces and has no significance for liquids.

Question 26

Which of the following is a common example of a wetting agent?

Accepted Answer

Soap, a surfactant that reduces surface tension and promotes wetting.

Answer

Mercury, a liquid metal with high surface tension and poor wetting properties.

Answer

Water, a polar solvent that can exhibit both wetting and non-wetting behavior depending on the surface.

Answer

Oil, a hydrophobic substance that tends to repel water.

Question 27

What is the primary mechanism responsible for the formation of emulsions?

Accepted Answer

The interfacial tension between two immiscible liquids drives the formation of droplets of one phase dispersed in the other.

Answer

Chemical reactions are not the primary mechanism for emulsion formation.

Answer

Electrostatic forces can influence emulsion stability but are not the main factor in their formation.

Answer

While Brownian motion plays a role in stabilizing emulsions, it is not the primary driver of formation.