Free Experimental Techniques in Chemistry MCQs with Answers
75 Experimental Techniques in Chemistry MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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75 questions · page 8 of 8
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.
Correct answer: Insoluble.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.
Correct answer: CaCl273. _ 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.
Correct answer: Solvent.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.
Correct answer: Benzoic Acid75. 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.
Correct answer: Benzoic acid