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Section 4.2.5. Separation of Dissolved Liquids PART 3

Total questions: 47

Worksheet time: 24mins

Name
Class
Date
1.

Which separation technique is particularly effective for dilute aqueous solutions of biomolecules?

a)

Chromatography

b)

Leaching

c)

Distillation

d)

Spray drying

2.

In solvent extraction, the rate of mass transfer is primarily governed by:

a)

Solvent viscosity

b)

Interfacial area and concentration gradient

c)

Solvent boiling point

d)

Phase density difference

3.

Which operating condition reduces entrainment losses in liquid–liquid extraction?

a)

Very high agitation speed

b)

Controlled agitation with proper settling time

c)

Increasing solvent polarity

d)

Operating at supercritical pressure

4.

The “distribution coefficient” in solvent extraction represents:

a)

Ratio of solvent viscosity to density

b)

Ratio of solute concentration in solvent phase to that in feed phase

c)

Fraction of solute lost

d)

Solvent-to-feed ratio

5.

The minimum number of extraction stages required for a target separation is estimated using:

a)

McCabe–Thiele method

b)

Perry–Greenwood chart

c)

Antoine equation

d)

Rayleigh equation

6.

For systems with close-boiling solvents, solvent extraction is favored over distillation because:

a)

Distillation is more energy intensive

b)

Distillation produces impure raffinate

c)

Distillation requires less equipment

d)

Extraction is always cheaper

7.

The effectiveness of leaching nuts and seeds depends on:

a)

Particle porosity and solvent diffusivity

b)

Color of the extract

c)

Operating at low pH

d)

Shape of the particles only

8.

Which parameter is most critical in adsorption processes?

a)

Particle color

b)

Surface area of the adsorbent

c)

Solvent miscibility

d)

Molecular weight of the solvent

9.

Ion exchange resins are generally classified into:

a)

Strong acid, weak acid, strong base, weak base

b)

Cationic and anionic only

c)

Porous and nonporous

d)

Polar and nonpolar

10.

A common adsorbent used in removing organic impurities from aqueous solutions is:

a)

Bentonite

b)

Activated carbon

c)

Silica sand

d)

Resin

11.

Chromatography is especially advantageous in biochemical product recovery because:

a)

It operates at low temperatures, avoiding denaturation

b)

It requires no solvents

c)

It is faster than filtration

d)

It does not require equilibrium stages

12.

In counter-current leaching, solvent economy is maximized by:

a)

Recycling solvent through multiple stages

b)

Using single-pass solvent flow

c)

Eliminating decanters

d)

Operating at high temperature only

13.

The main disadvantage of mixer-settlers in solvent extraction is:

a)

Limited throughput due to large settling area requirements

b)

High solvent consumption

c)

Continuous operation is impossible

d)

Lack of agitation control

14.

Which parameter best describes solvent selectivity in liquid–liquid extraction?

a)

Solvent density difference

b)

Separation factor

c)

Solvent refractive index

d)

Extraction pressure

15.

A system where uranium is extracted from nitric acid solution is an example of:

a)

Solvent extraction with immiscible organic solvent

b)

Adsorption

c)

Ion exchange

d)

Distillation

16.

In chromatography, separation is achieved because components:

a)

Have equal distribution between phases

b)

Partition differently between stationary and mobile phases

c)

Dissolve only in solvents

d)

Migrate at the same velocity

17.

Which of the following makes solvent extraction attractive for heat-sensitive materials?

a)

It operates at ambient temperatures

b)

It requires less solvent

c)

It uses high vacuum

d)

It eliminates raffinate recovery

18.

Leaching of oil from soybean flakes typically uses which solvent?

a)

Acetone

b)

Hexane

c)

Methanol

d)

Carbon tetrachloride

19.

In ion exchange, the exhaustion of resin means:

a)

Resin loses color

b)

Active sites are fully occupied by counter-ions

c)

Resin becomes insoluble

d)

Resin dissolves in water

20.

Which regeneration agent is used for cation exchange resins in water softening?

a)

Sodium chloride solution

b)

Sulfuric acid

c)

Ethanol

d)

Calcium hydroxide

21.

In adsorption, breakthrough curves are used to determine:

a)

Resin pore size

b)

Bed exhaustion time

c)

Solvent density

d)

Settling rate

22.

Which chromatography type is most widely used for protein purification?

a)

Thin layer chromatography

b)

Ion-exchange chromatography

c)

Gas chromatography

d)

Paper chromatography

23.

The primary advantage of column chromatography over batch methods is:

a)

Higher resolution and continuous separation

b)

No need for solvents

c)

Faster drying of solids

d)

Ability to separate immiscible liquids

24.

In solvent extraction, emulsion formation can be minimized by:

a)

Using low interfacial tension solvents

b)

Optimizing agitation intensity

c)

Adding large amounts of surfactants

d)

Decreasing settling time drastically

25.

The driving force for ion exchange processes is:

a)

Pressure difference

b)

Electrostatic affinity of ions to functional groups on resin

c)

Solvent evaporation

d)

Osmotic pressure

26.

A key difference between leaching and solvent extraction is that:

a)

Leaching operates on solid–liquid systems

b)

Leaching produces raffinate

c)

Solvent extraction requires drying

d)

Leaching always uses organic solvents

27.

A countercurrent washing system in leaching helps to:

a)

Reduce solvent recovery

b)

Minimize residual solute in solids

c)

Increase particle size

d)

Prevent diffusion

28.

Which factor primarily affects the separation speed in adsorption columns?

a)

Bed height and particle size

b)

Solvent polarity

c)

Temperature of the extract

d)

Density of the raffinate

29.

Chromatography provides high separation efficiency because:

a)

Multiple equilibria are established during migration

b)

It requires large volumes of solvent

c)

Components remain immiscible

d)

Mobile phase remains stagnant

30.

Which method is often used for scale-up of solvent extraction equipment?

a)

Sigma (Σ) theory

b)

Antoine equation

c)

Reynold’s analogy

d)

Stokes’ law

31.

In adsorption, desorption of solute is usually achieved by:

a)

Heating or solvent washing

b)

Crushing the adsorbent

c)

Increasing pressure

d)

Freezing the column

32.

In ion exchange water softening, hardness is mainly caused by:

a)

Sodium and potassium ions

b)

Calcium and magnesium ions

c)

Iron and copper ions

d)

Chloride and sulfate ions

33.

Leaching efficiency improves with:

a)

Smaller particle size and higher solvent penetration

b)

Larger particle size

c)

Higher solvent viscosity

d)

Lack of agitation

34.

In chromatography, the retention factor (Rf) measures:

a)

Ratio of distance traveled by solute to solvent front

b)

Solvent density difference

c)

Diffusivity of solute in solvent

d)

Interfacial tension

35.

Which industrial process uses adsorption extensively?

a)

Decolorization of sugar solutions

b)

Distillation of crude oil

c)

Extraction of palm oil

d)

Ion exchange in water treatment

36.

Solvent recovery is critical in extraction processes because:

a)

Solvent cost and environmental concerns

b)

Raffinate has no value

c)

Extraction is irreversible

d)

Solvent is always consumed

37.

Which is a typical case where adsorption is preferred over solvent extraction?

a)

Trace organic removal from water

b)

Recovery of oil from seeds

c)

Extraction of metals from acid solutions

d)

Large-scale distillation

38.

The selectivity of ion exchange resins depends on:

a)

Type of functional groups present

b)

Color of the solution

c)

Solvent boiling point

d)

Flow rate

39.

Chromatography columns often require:

a)

A stationary phase packed with solid or coated liquid

b)

Two immiscible solvents

c)

Continuous agitation

d)

Vacuum operation

40.

The equilibrium distribution of solute in extraction is influenced by:

a)

Solvent-to-feed ratio

b)

Particle size of solid feed

c)

Bed porosity

d)

Crystallization rate

41.

In continuous countercurrent leaching, performance is measured by:

a)

Solvent viscosity

b)

Solute recovery efficiency per stage

c)

Raffinate density

d)

Bed height

42.

A refinery wants to remove trace sulfur compounds from a hydrocarbon stream without high energy costs. The best method is:

a)

Solvent extraction

b)

Adsorption using activated carbon

c)

Ion exchange

d)

Leaching

43.

Which solvent property most strongly determines phase disengagement in extraction?

a)

Polarity difference with feed solvent

b)

Refractive index

c)

Color

d)

pH

44.

Leaching kinetics are controlled mainly by:

a)

Diffusion through solid pores

b)

Solvent density

c)

Heat of vaporization

d)

Adsorption equilibria

45.

In water softening by ion exchange, regeneration with NaCl restores:

a)

Na⁺ ions on the resin

b)

Ca²⁺ and Mg²⁺ ions

c)

K⁺ ions

d)

Sulfate groups

46.

Which chromatography method separates based on molecular size?

a)

Gel filtration chromatography

b)

Ion exchange chromatography

c)

Affinity chromatography

d)

Partition chromatography

47.

Which factor reduces solvent requirements in extraction?

a)

High distribution coefficient of solute

b)

High solvent miscibility

c)

Low solute diffusivity

d)

Smaller interfacial area

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