This set of Extractive Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Refining”.
1. Which of the following conditions can be created properly for the transfer of impurities away from the metallic phases?
a) Climatic
b) Thermodynamic
c) Hydrostatic
d) Physical
View Answer
Explanation: During an extraction process, we can create proper thermodynamic and kinetic conditions for the transfer of impurities from the metallic phases. This can be achieved by creating a proper slag. A good metal-slag separation can also facilitate the above-mentioned approach for the purification of metals.
2. Which of the following is one of the basic approach for the purification of metals?
a) Production of pure metal compounds
b) Production of impure metal compounds
c) Production of improper slag
d) Production of slag in bulk
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Explanation: One of the basic approaches for the purification of metals is the production of pure metal compounds so that it can be further reduced to pure metals. This process is done for a large number of reactive and rarer metals.
3. Which of the following approach for purification of metals is used for the production of inexpensive metals like iron, lead, tin etc.?
a) Production of pure metal compounds
b) Creation of proper thermodynamic condition
c) Creation of proper kinetic condition
d) Production of impure bulk metal
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Explanation: Production of impure bulk metal during the extraction process is the most common method. It is used for the purification of metals which are inexpensive and are produced in large quantities like iron, tin, lead etc.
4. What is the advantage of conducting sublimation at low temperature?
a) Decomposition of heat-sensitive impurities are reduced
b) Corrosion is increased
c) Process becomes economical
d) Energy consumption is reduced
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Explanation: If the process of sublimation is conducted at low temperatures then we can reduce the formation of heat-sensitive impurities. It can also minimize the corrosion of the metal. After sublimation, we are left behind with the non-volatile particles.
5. Which of the following properties of the metal is considered high during the sublimation on a compound?
a) Melting point
b) Freezing point
c) Vapour pressure
d) Atomic number
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Explanation: Compound of metal with high vapour pressure can be easily sublimed in air. The pressure which we refer to is the partial pressure of the compound and not the pressure of the whole system. At normal pressure, the transition from solid to gaseous state requires an intermediate liquid phase.
6. In the physical methods of the refining processes, no chemical reaction takes place.
a) True
b) False
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Explanation: The physical methods of the refining processes involves no chemical reactions. It separate impurities using unit operations by physical means. There is a change in phase that takes place in the following operations.
7. Which of the following is not a physical method of the refining processes?
a) Selective distillation
b) Chemical vapour deposition
c) Zone refining
d) Parke’s process
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Explanation: Refining processes involves physical, chemical and electrochemical methods. Chemical vapour deposition is a chemical method. Physical methods include selective distillation, zone refining, selective dissolution and liquation.
8. On what factor does the liquation technique based on?
a) Immiscibility of phases
b) The difference in freezing points of the alloy components
c) The difference in the atomic number of the alloy elements
d) The difference in the molecular weight of the components of the alloy
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Explanation: In the liquation process, we selectively melt the components of an alloy. The factors on which the liquation process is carried out are the difference in melting points and densities of the alloy components. Liquation process is carried out based on the immiscibility of the phases.
9. Which process is used to refine an impure compound by dissolving it in a suitable acid or alkaline medium?
a) Solvent extraction
b) Partition
c) Selective dissolution
d) Stripping
View Answer
Explanation: Selective dissolution is a process in which an impure compound is dissolved in a suitable solvent metal. Parke’s process is an example of one such process which uses selective dissolution. In this process, different chemical reagents are used to selectively extract metal components from ore.
10. In electrolytic refining, what is used as anode?
a) Pure metal
b) Metal ore to be refined
c) Catalyst
d) Carbon
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Explanation: In electrolytic refining, the anode is made of the metal ore to be refined. Pure metal gets deposited on the cathode. The cathode is sometimes made of pure metal. The electrolyte consists of an ionizable salt of the metal.
11. During electrolytic refining, what are the impurities which settle at the bottom of the cell below anode called?
a) Rust
b) Cathode slime
c) Noble metals
d) Anode slime
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Explanation: During electrolytic refining, if the impurities are very much noble then they remain at the anode. After the consumption of anode, they get settled down at the bottom of the cell below anode. These impurities are called anode slime.
12. Which principle is used more efficiently in the zone refining process?
a) Fractional distillation
b) Fractional crystallization
c) Electrolytic refining
d) Selective dissolution
View Answer
Explanation: The principles of fractional crystallization is used more efficiently in the zone refining process. Zone refining process is used to produce very pure metals in the laboratory. The material used at the beginning of this process should contain impurity in low concentration.
13. In which type of refining method, impurities are converted to compounds by adding refining agents?
a) Physical
b) Chemical
c) Electro-chemical
d) Ionic
View Answer
Explanation: In Chemical methods, the impurities are converted to compounds using some refining agents like oxygen, sulphur, chlorine etc. The refining agents react preferentially with the elements. After that, the compounds are separated from the metals.
14. What is the name of the process in which the deposition of metal from vapours take place?
a) Chemical vapour deposition
b) Physical vapour deposition
c) Condensation
d) Vaporization
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Explanation: Chemical vapour deposition is the process in which the deposition of metal from vapours take place. The process varies depending on the nature of vapours. Carbonyl process and de Boer process are some of the chemical vapour deposition processes.
15. Which of the following refining method is most important commercially?
a) Physical methods
b) Chemical methods
c) Electrochemical methods
d) Ionic methods
View Answer
Explanation: Electrochemical methods are the most important compared to others commercially because of its versatility and flexibility. It produces metals of very high purity. This process can separate more as well as less reactive impurities from the metals.
Sanfoundry Global Education & Learning Series – Extractive Metallurgy.
To practice all areas of Extractive Metallurgy, here is complete set of Multiple Choice Questions and Answers.
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