Free Experimental Techniques in Chemistry MCQs with Answers

71. The process of filtration is used to separate particles _ from liquids.

• A. Radial.
• B. Angular.
• C. Insoluble.
• D. Soluble

Explanation: The insoluble solid particles can be separated from the liquid by filtration. A filter paper is made into a cone & placed in a funnel, the liquid flows through the cone and solid particles remain in the cone.

72. Which is the best drying agent in desiccators?

• A. KOH
• B. Gypsum
• C. CaCl2
• D. Silica sand

Explanation: The anhydrous calcium chloride will absorb any water (including condensation, vapour etc) in its environment. It effectively traps that water by changing its molecular make-up.

73. _ extraction is controlled by partition law.

• A. Iodine.
• B. Benzoic acid.
• C. Solvent.
• D. Stationery.

Explanation: Solvent extraction is an equilibrium process controlled by distribution law or partition law. It states that a solute distributes itself between two immiscible liquids in a constant ratio of concentrations irrespective of the amount of solute added. The law is based on experimental evidence.

74. The acid which can be purified by the sublimation is:

• A. Acetic Acid
• B. Oxalic Acid
• C. Benzoic Acid
• D. Citric Acid

Explanation: Explanation:Benzoic acid has a high melting point (122°C) and a low vapor pressure, which allows it to sublime at room temperature and atmospheric pressure. Hence, the acid which can be purified by the sublimation is benzoic acid.Acetic acid has a low boiling point (118.1°C) and cannot be purified by sublimation. Oxalic acid has a decomposition temperature lower than its melting point, so it cannot be purified by sublimation. Citric acid has a decomposition temperature lower than its melting point, so it cannot be purified by sublimation.

75. Sublimation is used to purify:

• A. Ammonium sulphate
• B. Sodium chloride
• C. Benzoic acid
• D. Lead carbonate

Explanation: A is incorrect as ammonium sulphate is purified through centrifuging.B is incorrect as sodium chloride is purified by crystallization.C is correct as benzoic acid is purified through sublimation.D is incorrect as lead carbonate is purified through sulfation, desulfurization leaching, distillation and carbonization.

76. Which one is the separating technique:

• A. Deliquescence
• B. Fluorescence
• C. Phosphorescence
• D. Solvent extraction

Explanation: Solvent extraction is used for separation of mixtures

77. The partition coefficients of Iodine distribution between two immiscible liquids, water and carbon (tetrachloride) is given below:Choose the correct statement about the system:

• A. Iodine is extracted from CCl4 layer by water
• B. Iodine is extracted from aqueous layer by CCl4
• C. Iodine is more soluble in water than CCl4
• D. The value of K depends on the amount of Iodine added

Explanation: Iodine vastly prefers to dissolve in CCl4 , thus it migrates from the aqueous (H2O) phase into the non-aqueous (CCl4) phase , thus we say that CCl4 extracts the iodine from the aqueous phase.

78. For the separation of gases from a mixture we use:

• A. Simple diffusion
• B. Fractional distillation
• C. Chromatography
• D. Graham's law of diffusion

Explanation: Fractional distillation is the special technique which is used for separation of mixture of two gases

79. Which one of the following is used as a drying agent?

• A. NaHCO3
• B. CaCO3.H2O
• C. CaCl2 anhydrous
• D. Na2SO4.H2O

Explanation: CaCl2 (anhydrous calcium chloride): Calcium chloride is a widely used drying agent due to its strong hygroscopic properties. It effectively absorbs moisture from the air, making it useful for drying applications in laboratories, industries, and even for de-icing roads.