JEE Main - Purification techniques crystallization sublimation distillation extraction chromatography Online Test (MCQ Quiz)

1. Which purification technique is most suitable for separating a solid solute from a liquid solvent when the solute is soluble in the solvent?

A) Distillation B) Crystallization C) Sublimation D) Chromatography

2. When can sublimation be effectively used as a purification method?

A) When the compound is non-volatile B) When the compound decomposes upon heating C) When the compound sublimes readily on heating D) When the compound is highly soluble in water

3. Simple distillation is primarily used to separate liquids with a significant difference in which property?

A) Density B) Boiling point C) Viscosity D) Solubility

4. What is the main principle behind fractional distillation?

A) Difference in solubility B) Difference in vapor pressure and boiling point C) Difference in sublimation temperature D) Difference in density

5. Which type of distillation is used to separate liquids with very close boiling points?

A) Simple distillation B) Vacuum distillation C) Steam distillation D) Fractional distillation

6. Vacuum distillation is employed for purifying compounds that have which characteristic?

A) Very low boiling points B) High boiling points and decompose at atmospheric pressure C) Tendency to sublime D) High solubility in water

7. Steam distillation is a useful technique for purifying which class of compounds?

A) Ionic compounds B) Inorganic salts C) Heat-labile organic compounds immiscible with water D) Highly volatile liquids

8. In solvent extraction, the separation is based on the difference in the:

A) Boiling points of the components B) Solubilities of the components in two immiscible solvents C) Sublimation temperatures of the components D) Crystal structures of the components

9. Which of the following is a common immiscible solvent pair used in extraction?

A) Water and ethanol B) Water and acetone C) Water and carbon tetrachloride D) Ethanol and acetone

10. What is the primary goal of recrystallization?

A) To separate liquids B) To purify a solid compound C) To isolate gases D) To determine the molecular weight

11. For effective recrystallization, the desired compound should be soluble in the solvent at high temperatures and insoluble at low temperatures. What is the opposite property desired for impurities?

A) Highly soluble at both high and low temperatures B) Insoluble at both high and low temperatures C) Soluble at low temperatures and insoluble at high temperatures D) Volatile at high temperatures

12. Which of these is NOT a common solvent for recrystallization?

A) Water B) Ethanol C) Benzene D) Hydrogen

13. What is the process of separating components of a mixture by passing it through a stationary phase?

A) Distillation B) Crystallization C) Extraction D) Chromatography

14. In chromatography, the mobile phase is:

A) The solid material packed in the column B) The liquid or gas that carries the sample through the stationary phase C) The separated components of the mixture D) The substance being purified

15. The stationary phase in column chromatography is typically:

A) A liquid solvent B) A gas C) A solid adsorbent like silica gel or alumina D) The mobile phase itself

16. Which type of chromatography is used to separate compounds based on their differing affinities for the stationary and mobile phases?

A) Paper chromatography B) Thin-layer chromatography C) Column chromatography D) All of the above

17. Paper chromatography is a type of partition chromatography where the stationary phase is:

A) Silica gel B) Alumina C) Water adsorbed on cellulose fibers D) A gas

18. In Thin-Layer Chromatography (TLC), the stationary phase is coated on a:

A) Glass plate B) Plastic sheet C) Metal foil D) Paper sheet

19. The separation in TLC is achieved by the differential migration of components on the stationary phase due to their interactions with the mobile phase. This is known as:

A) Distillation B) Crystallization C) Chromatographic separation D) Extraction

20. What does the Rf value represent in paper and thin-layer chromatography?

A) The distance traveled by the solvent front B) The distance traveled by the substance divided by the distance traveled by the solvent front C) The time taken for a substance to move D) The polarity of the stationary phase

21. A compound that is more strongly adsorbed to the stationary phase will have a Rf value that is:

A) Higher B) Lower C) Equal to 1 D) Zero

22. What is the primary purpose of using an anti-bumping granule during distillation?

A) To increase the boiling point of the liquid B) To ensure smooth boiling by preventing superheating C) To absorb impurities D) To cool down the vapor

23. In crystallization, what is the term for a saturated solution that contains more dissolved solute than it theoretically should be able to hold at a given temperature?

A) Dilute solution B) Unsaturated solution C) Supersaturated solution D) Normal solution

24. Which technique is most appropriate for purifying volatile organic compounds that are thermally stable?

A) Crystallization B) Sublimation C) Simple Distillation D) Extraction

25. When separating a mixture of iodine and sand, which purification method is most effective?

A) Distillation B) Crystallization C) Sublimation D) Extraction with water

26. What is the role of the condenser in a distillation apparatus?

A) To heat the liquid B) To collect the distillate C) To cool the vapor and condense it into liquid D) To measure the boiling point

27. Which type of chromatography is used for separating large biomolecules like proteins and nucleic acids based on size?

A) Gas Chromatography (GC) B) High-Performance Liquid Chromatography (HPLC) C) Gel Permeation Chromatography (GPC) D) Ion-Exchange Chromatography

28. In gas chromatography, the mobile phase is a:

A) Liquid solvent B) Solid adsorbent C) Inert gas like helium or nitrogen D) Water

29. What is the main advantage of using HPLC over traditional column chromatography?

A) Lower resolution B) Slower separation speed C) Higher resolution and faster separation D) Use of less sophisticated detectors

30. The process of separating a compound from a mixture by dissolving it in a suitable solvent is called:

A) Filtration B) Evaporation C) Extraction D) Decantation

31. Which purification technique relies on the principle of differential partitioning of a solute between two immiscible phases?

A) Distillation B) Crystallization C) Sublimation D) Extraction

32. What is the primary advantage of crystallization over distillation for purifying solids?

A) It can separate liquids with close boiling points. B) It can purify compounds that decompose upon heating. C) It is faster for large quantities. D) It requires less solvent.

33. Which of the following is a common application of sublimation in purification?

A) Purification of water B) Purification of benzoic acid C) Separation of ethanol and water D) Separation of salt and sand

34. A mixture of camphor and naphthalene can be purified using which method?

A) Simple Distillation B) Fractional Distillation C) Sublimation D) Steam Distillation

35. In fractional distillation, the fractionating column increases the surface area for repeated vaporizations and condensations, leading to better separation. What is commonly packed inside the column?

A) Glass beads, rings, or saddles B) Activated charcoal C) Cotton wool D) Sand

36. When is steam distillation particularly useful for purifying essential oils from plant materials?

A) When the oils are highly soluble in water B) When the oils decompose at their boiling points C) When the oils are denser than water D) When the oils are volatile with steam but immiscible with water

37. What is the purpose of a separatory funnel in the process of extraction?

A) To heat the mixture B) To mix the two immiscible liquids thoroughly C) To allow the separation of two immiscible liquid layers D) To filter out solid impurities

38. In crystallization, what is the process of removing dissolved impurities by washing the crystals with a small amount of cold solvent?

A) Filtration B) Drying C) Washing D) Dissolution

39. Which chromatographic technique is best suited for separating volatile compounds at high temperatures?

A) Paper Chromatography B) Thin-Layer Chromatography C) Gas Chromatography (GC) D) Column Chromatography

40. In chromatography, the component that moves faster with the mobile phase is the one that has:

A) Higher affinity for the stationary phase B) Lower affinity for the stationary phase C) Higher molecular weight D) Lower polarity

41. What is the primary advantage of using crystallization for purification?

A) It can separate liquids. B) It can purify compounds that are gases. C) It often yields highly pure crystalline solids. D) It is effective for thermally unstable compounds.

42. Which method is used to purify solids that sublime easily, like iodine or naphthalene?

A) Distillation B) Crystallization C) Sublimation D) Extraction

43. The process of separating components of a mixture based on their different boiling points is known as:

A) Crystallization B) Sublimation C) Distillation D) Extraction

44. Which of the following is a characteristic of a good solvent for crystallization?

A) It dissolves the compound well at all temperatures. B) It reacts with the compound. C) It dissolves the compound poorly at high temperatures. D) It dissolves the compound well at high temperatures and poorly at low temperatures.

45. What is the primary purpose of using a Buchner funnel and filter paper in crystallization?

A) To heat the solvent B) To collect the purified crystals by filtration C) To dissolve the solid D) To evaporate the solvent

46. Which technique is used to separate liquids that form azeotropes (mixtures with constant boiling points)?

A) Simple Distillation B) Fractional Distillation C) Azeotropic Distillation D) Vacuum Distillation

47. In extraction, if the desired compound is more soluble in the organic layer than the aqueous layer, which solvent would you choose for extraction from an aqueous solution?

A) Water B) Ethanol C) A non-polar organic solvent like diethyl ether or dichloromethane D) Acetone

48. What is the primary limitation of sublimation as a purification technique?

A) It is only suitable for liquids. B) It is only suitable for compounds that do not sublime. C) It cannot separate mixtures containing non-volatile impurities. D) It requires very high temperatures.

49. Which of the following is a common application of chromatography in organic chemistry?

A) Separating salt from water B) Purifying crude reaction products C) Removing water from ethanol D) Melting ice

Purification techniques crystallization sublimation distillation extraction chromatography - Online Test

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