Purification: distillation, crystallisation, chromatography

27 questions on Purification: distillation, crystallisation, chromatography from the Structural Identification and Practical Organic Chemistry chapter: 5 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• Steam distillation is used to purify an organic liquid that is NEET level
• Which of the following mixtures can be separated by sublimation? NEET level
• Glycerol is purified by distillation under reduced pressure because it NEET level
• In thin layer chromatography a spot has moved 3.2 cm from the baseline while the solvent front has moved 8.0 cm. The R_f value of the compound is NEET level
• Column chromatography separates the components of a mixture mainly on the basis of their NEET level
• A mixture of 2-nitrophenol and 4-nitrophenol is steam distilled. The distillate contains JEE Main level
• Chloroform (b.p. 334 K) is mixed with aniline (b.p. 457 K). The simplest adequate method of separating the two liquids is JEE Main level
• Two miscible liquids P (b.p. 349 K) and Q (b.p. 353 K) form an ideal solution. Which method is suitable to separate them? JEE Main level
• The solubility of a solid (g per 100 mL) in four solvents at 25 degC and at the boiling point is: A, 20 and 22; B, 0.5 and 0.6; C, 1.0 and 18; D, 25 and 40. The... JEE Main level
• On a silica gel TLC plate, spots A and B are at 2.4 cm and 4.5 cm from the baseline and the solvent front is at 6.0 cm. The R_f values of A and B and the compou... JEE Main level
• An ether solution contains benzoic acid, phenol, aniline and naphthalene. It is shaken with aqueous NaHCO3. The compound transferred to the aqueous layer is JEE Main level
• A mixture is placed on a silica gel column and eluted with hexane. Among octane, octan-1-ol, octanoic acid and octanamide, the first to emerge from the column i... JEE Main level
• Distillation under reduced pressure lowers the boiling temperature of a liquid because JEE Main level
• Bromobenzene (immiscible with water) is steam distilled at 1 atm. The mixture distils at a temperature that is JEE Main level
• Which statements about purification of a solid by crystallisation are correct? JEE Main level
• A little activated charcoal is added to a hot aqueous solution of impure benzoic acid before hot filtration. Its purpose is to JEE Main level
• Bromobenzene (M = 157) is steam distilled at a temperature where the vapour pressure of water is 634 mmHg and the total pressure is 760 mmHg (M of water = 18). ... JEE Advanced level
• An ether solution contains benzoic acid, phenol, aniline and naphthalene. It is extracted successively with (1) dilute aqueous HCl, (2) aqueous NaHCO3, (3) aque... JEE Advanced level
• A solid mixture of naphthalene, sodium chloride and sand is to be separated into its three components. Which procedure achieves this? JEE Advanced level
• In a TLC experiment the solvent front moved 7.5 cm above the baseline. Compound X has R_f = 0.60 and compound Y has R_f = 0.32. The distance between the centres... JEE Advanced level
• A 12.0 g sample contains 90% of compound A and 10% of an impurity that stays dissolved throughout. The solubility of A is 24.0 g/100 mL in a solvent at its boil... JEE Advanced level
• Ethanol and water form a minimum-boiling azeotrope containing 95.6% ethanol by mass. A mixture containing 50% ethanol by mass is subjected to efficient fraction... JEE Advanced level
• Which of the following are purified by steam distillation from non-volatile impurities (at atmospheric pressure)? JEE Advanced level
• For a TLC experiment, which statements are correct? JEE Advanced level
• Which statements about distillation methods are correct? JEE Advanced level
• Which statements about chromatography are correct? JEE Advanced level
• A solute has partition coefficient K = C_ether/C_water = 10. A 100 mL aqueous solution contains 5.0 g of the solute. It is extracted twice with 50 mL portions o... JEE Advanced level