TRB PG Assistant - Classical separation techniques: column, thin layer and paper chromatography Question Bank with Options

1. When using a polar stationary phase (like silica) and a polar mobile phase in column chromatography, compounds that are less polar will tend to:

A) Interact more strongly with the stationary phase and elute later

B) Interact less strongly with the stationary phase and elute earlier

C) Be insoluble in the mobile phase

D) Decompose during elution

2. What is the term for the process of separating components based on their differential distribution between a liquid stationary phase and a gas mobile phase?

A) Paper Chromatography

B) Thin-Layer Chromatography

C) Column Chromatography

D) Gas Chromatography

3. Which classical separation technique is most suitable for qualitative analysis of small amounts of samples, such as identifying components in a plant extract?

A) Column Chromatography

B) Paper Chromatography

C) Thin-Layer Chromatography (TLC)

D) All are equally suitable

4. In column chromatography, what is the effect of using a finer particle size for the stationary phase material?

A) Decreased surface area and poorer separation

B) Increased surface area and improved separation efficiency

C) Faster flow rate of the mobile phase

D) Reduced capacity for the sample

5. What is the primary advantage of using silica gel as a stationary phase in TLC compared to paper?

A) It is cheaper and easier to handle

B) It offers a wider range of polarities for stationary phase modification

C) It provides more reproducible separations and higher resolution

D) It is always used with aqueous mobile phases

6. Which factor is LEAST likely to affect the Rf value of a compound in paper chromatography?

A) The composition of the mobile phase

B) The type of paper used

C) The ambient temperature of the laboratory

D) The concentration of the sample applied

7. What is the primary role of the mobile phase in Thin-Layer Chromatography (TLC)?

A) To act as the solid support

B) To bind the sample components

C) To carry the sample components up the plate via capillary action

D) To react with the sample components to produce color

8. In column chromatography, 'channeling' refers to:

A) The even flow of the mobile phase through the stationary phase

B) The formation of pathways in the stationary phase, leading to poor separation

C) The detection of separated components

D) The process of loading the sample

9. Which of the following is a disadvantage of using paper chromatography for quantitative analysis?

A) Paper is a very stable and inert material

B) It is difficult to obtain precise quantitative results due to paper variability and charring

C) The solvents used are usually non-toxic

D) The separation is usually very fast

10. What is the 'spotting line' in TLC and paper chromatography?

A) The line where the solvent front stops

B) The line where the sample is initially applied to the stationary phase

C) The line indicating the optimal separation distance

D) The line used for comparison with standards

11. In paper chromatography, if the mobile phase is too polar, what is the likely outcome for a separation involving polar and nonpolar compounds?

A) Polar compounds will move faster than nonpolar compounds

B) Nonpolar compounds will move faster than polar compounds

C) All compounds will likely have very high Rf values and poor separation

D) All compounds will remain at the origin

12. What is the primary basis for separation in partition chromatography?

A) Differences in molecular size

B) Differences in charge

C) Differences in solubility between two immiscible liquid phases

D) Differences in adsorption strength to a solid surface

13. Thin-Layer Chromatography (TLC) is often used as a preliminary technique to optimize conditions for which other chromatographic method?

A) Paper Chromatography

B) Gas Chromatography

C) Column Chromatography

D) Ion-Exchange Chromatography

14. In column chromatography, what is the term for the component that moves fastest through the column?

A) Retained component

B) Early eluting component

C) Late eluting component

D) Immobile component

15. What is the stationary phase in classical paper chromatography primarily composed of?

A) Hydrophobic cellulose fibers

B) Adsorbent particles like silica

C) Bound water molecules within the cellulose matrix

D) A nonpolar polymer coating

16. Which statement is TRUE regarding the relationship between Rf value and solvent polarity in normal-phase TLC?

A) Increasing solvent polarity decreases Rf values

B) Increasing solvent polarity increases Rf values

C) Solvent polarity has no effect on Rf values

D) Rf values are independent of solvent polarity

17. In column chromatography, what is the advantage of using a gradient elution compared to an isocratic elution?

A) It is simpler to set up

B) It can provide better separation for complex mixtures with a wide range of component polarities

C) It always results in faster separation

D) It requires less solvent

18. What is the phenomenon where components of a mixture travel at different rates through the stationary phase due to varying affinities?

A) Diffusion

B) Advection

C) Differential migration

D) Equilibration

19. Which chromatographic technique is most suitable for separating a mixture of very similar, non-volatile organic compounds?

A) Paper Chromatography

B) Column Chromatography

C) Thin-Layer Chromatography (TLC)

D) All are equally suitable

20. What is the purpose of the 'developing chamber' in TLC and paper chromatography?

A) To hold the solvent and allow it to saturate the atmosphere

B) To dry the separated components

C) To heat the sample

D) To collect the eluent

21. Which of the following is a common method to visualize separated spots in TLC or paper chromatography when the compounds are colorless?

A) Heating the plate

B) Using a UV lamp or chemical staining reagents

C) Adding a strong acid

D) Cooling the plate

22. In paper chromatography, if a compound has a very low Rf value, it implies that the compound:

A) Is highly soluble in the mobile phase and weakly adsorbed to the stationary phase

B) Is weakly soluble in the mobile phase and strongly adsorbed to the stationary phase

C) Is highly soluble in both phases

D) Does not interact with either phase

23. When performing reverse-phase chromatography, which type of mobile phase is typically used for optimal separation?

A) Highly polar solvent (e.g., water)

B) Nonpolar solvent (e.g., hexane)

C) A mixture of polar and nonpolar solvents

D) An acidic solution

24. What is the primary characteristic of the stationary phase in 'reverse-phase' chromatography?

A) Nonpolar

B) Polar

C) Acidic

D) Basic

25. What is the primary characteristic of the stationary phase in 'normal-phase' chromatography?

A) Nonpolar

B) Polar

C) Ionic

D) Metallic

26. In column chromatography, a longer column generally leads to:

A) Faster elution

B) Poorer separation

C) Better separation

D) Increased sample decomposition

27. Which of the following is a limitation of paper chromatography?

A) It can handle very large sample sizes

B) The stationary phase (water held by cellulose) can be difficult to control

C) It provides very fast separations

D) It is suitable for separating thermally labile compounds

28. What does the 'T' in TLC stand for?

A) Temperature

B) Thin

C) Time

D) Transport

29. In column chromatography, what is the effect of increasing the polarity of the mobile phase when using a normal-phase stationary phase (like silica gel)?

A) Components will elute faster

B) Components will elute slower

C) Separation will not be affected

D) The stationary phase will dissolve

30. Which of these is NOT a typical application of Thin-Layer Chromatography (TLC)?

A) Monitoring reaction progress

B) Determining the purity of a compound

C) Separating complex mixtures for large-scale purification

D) Identifying compounds by comparing Rf values with standards

31. What is the term for the process where components are separated based on their differential partitioning between two immiscible liquid phases, one of which is immobilized on a solid support?

A) Adsorption Chromatography

B) Ion-Exchange Chromatography

C) Partition Chromatography

D) Size-Exclusion Chromatography

32. Paper chromatography can be used for quantitative analysis if the separated spots are visualized and then:

A) Scraped off and weighed

B) Eluted and their concentration measured spectrophotometrically

C) Assayed by titration

D) Heated until they decompose

33. In adsorption chromatography, the separation is based on the differences in the degree of adsorption of components onto the surface of the stationary phase. Which of the following is a common stationary phase for adsorption chromatography?

A) Water

B) Glycerol

C) Silica gel

D) Ethanol

34. What is 'overloading' in column chromatography?

A) Using too much stationary phase

B) Using too much mobile phase

C) Applying too much sample, leading to poor separation

D) Using a column that is too wide

35. Which of the following factors can influence the Rf value of a compound in TLC?

A) The size of the chromatography tank

B) The choice of stationary phase and mobile phase

C) The ambient temperature only

D) The color of the plate

36. What is the role of the solvent front in paper and thin-layer chromatography?

A) It is the point where the sample is applied

B) It marks the furthest point reached by the mobile phase

C) It indicates the position of the most strongly adsorbed component

D) It is the solvent used to dissolve the sample initially

37. Which type of chromatography is best suited for separating large quantities of material for preparative purposes?

A) Thin-Layer Chromatography (TLC)

B) Paper Chromatography

C) Column Chromatography

D) Affinity Chromatography

38. A compound that is more strongly adsorbed to the stationary phase (or more soluble in the stationary phase) will generally:

A) Travel faster and elute earlier

B) Travel slower and elute later

C) Not move from the origin

D) Decompose during the process

39. What is the primary purpose of developing a chromatogram in TLC or paper chromatography?

A) To evaporate the mobile phase

B) To allow the mobile phase to move up the plate/paper and separate the components

C) To heat the sample

D) To precipitate the components

40. Which statement best describes the 'stationary phase' in a chromatographic system?

A) The phase that moves and carries the sample

B) The phase that remains fixed and interacts with the sample components

C) The solvent used to dissolve the sample

D) The detector used to identify separated components

41. In column chromatography, the process of passing the mobile phase through the packed stationary phase to separate components is called:

A) Adsorption

B) Elution

C) Desorption

D) Precipitation

42. What is the main advantage of Thin-Layer Chromatography (TLC) over Paper Chromatography for many applications?

A) It is generally slower

B) It uses a more expensive stationary phase

C) It typically provides faster separations and sharper spots

D) It requires a larger sample size

43. In paper chromatography, the mobile phase moves through the stationary phase primarily due to:

A) Gravity

B) Centrifugal force

C) Capillary action

D) Evaporation

44. Paper chromatography utilizes a stationary phase composed of which material?

A) Silica gel

B) Alumina

C) Cellulose (paper)

D) Polymer beads

45. What is the 'Rf value' in chromatography?

A) The retention time of a compound

B) The ratio of the distance traveled by the solute to the distance traveled by the solvent front

C) The volume of solvent required to elute a compound

D) The temperature at which separation occurs

46. In Thin-Layer Chromatography (TLC), what is typically used as the stationary phase?

A) Water

B) Silica gel or alumina

C) A volatile organic solvent

D) Cellulose paper

47. Which type of chromatography is characterized by a stationary phase coated on a flat glass or plastic plate and a mobile phase that moves up the plate by capillary action?

A) Column Chromatography

B) Paper Chromatography

C) Thin-Layer Chromatography (TLC)

D) Gas Chromatography

48. What is the primary function of the mobile phase in column chromatography?

A) To bind strongly to the stationary phase

B) To carry the separated components out of the column

C) To stabilize the stationary phase

D) To react chemically with the sample components

49. In column chromatography, what serves as the stationary phase?

A) The liquid solvent used to elute the sample

B) A solid adsorbent packed into a vertical column

C) The sample mixture being separated

D) A gas used to carry the sample

50. What is the fundamental principle behind all chromatographic separation techniques?

A) Differences in boiling points of the components

B) Differences in solubility of the components in a solvent

C) Differential partitioning of components between a stationary phase and a mobile phase

D) Differences in the density of the components

Classical separation techniques: column, thin layer and paper chromatography - Question Bank