Here below some basic MCQ’s about “Extraction of metals like Iron and Copper” with answer and explanation for exam practice. Let’s check one by one.
1. Which of the following is the most suitable reducing agent for the extraction of iron from its ore?
- A) Carbon monoxide
- B) Aluminium
- C) Hydrogen
- D) Sodium
Answer: A) Carbon monoxide
Explanation: In the blast furnace, iron is extracted from its ore, hematite (Fe2O3). Carbon monoxide acts as the reducing agent at high temperatures. It reduces iron ore to molten iron:
Fe2O3+3CO→2Fe+3CO2
2. In the extraction of copper from copper pyrites (CuFeS2CuFeS2), the role of silica is to:
- A) Act as a reducing agent
- B) Act as a flux to remove impurities
- C) Act as an oxidizing agent
- D) Reduce copper oxide to copper
Answer: B) Act as a flux to remove impurities
Explanation: In the extraction of copper, silica (SiO2SiO2) acts as a flux. It reacts with iron oxide (formed from iron impurities in copper pyrites) to form slag (iron silicate), which is removed from the furnace: FeO+SiO2→FeSiO3(slag)
3. Which process is used for the extraction of copper from low-grade ores?
- A) Froth flotation
- B) Leaching
- C) Smelting
- D) Roasting
Answer: B) Leaching
Explanation: For low-grade copper ores, the hydrometallurgical process of leaching is used. In this process, the ore is treated with acid or bacteria to dissolve the copper, which is later recovered by processes like solvent extraction or electro-winning.
4. The reaction in the blast furnace that produces slag during the extraction of iron involves:
- A) Carbon dioxide and lime
- B) Iron ore and limestone
- C) Calcium silicate and hematite
- D) Calcium oxide and silica
Answer: D) Calcium oxide and silica
Explanation: In the blast furnace, limestone (calcium carbonate) decomposes into calcium oxide (CaOCaO) and carbon dioxide. The calcium oxide reacts with silica (an impurity in iron ore) to form calcium silicate (slag), which is removed from the furnace: CaO+SiO2→CaSiO3(slag) (slag)
5. Which of the following is the main impurity present in the iron ore hematite?
- A) Silica
- B) Phosphorus
- C) Carbon
- D) Sulfur
Answer: A) Silica
Explanation: In the extraction of iron from hematite, the main impurity is silica (SiO2SiO2). This impurity is removed as slag by reacting with lime in the blast furnace.
6. Roasting of sulphide ores produces which of the following?
- A) Metal oxide
- B) Metal carbonate
- C) Metal sulphide
- D) Metal chloride
Answer: A) Metal oxide
Explanation: During roasting, sulphide ores are heated in the presence of oxygen, which converts the sulphide to oxide and releases sulfur dioxide gas: 2ZnS+3O2→2ZnO+2SO2
7. The froth flotation process is suitable for the concentration of which type of ores?
- A) Oxide ores
- B) Sulphide ores
- C) Carbonate ores
- D) Chloride ores
Answer: B) Sulphide ores
Explanation: Froth flotation is used to concentrate sulphide ores. In this process, the ore is mixed with water and a frothing agent, and air is blown through the mixture. The sulphide particles attach to the air bubbles and float to the surface, while the gangue sinks to the bottom.
8. Which of the following methods is used to extract iron from its ore?
- A) Electrolysis
- B) Reduction with carbon
- C) Leaching
- D) Magnetic separation
Answer: B) Reduction with carbon
Explanation: Iron is extracted from its ores (mainly hematite) by reduction with carbon in a blast furnace. The carbon reduces the iron oxide to molten iron, and carbon dioxide is produced as a byproduct.
9. What is the purpose of adding limestone in the extraction of iron in a blast furnace?
- A) To reduce iron ore to iron
- B) To remove impurities as slag
- C) To oxidize iron
- D) To produce carbon dioxide
Answer: B) To remove impurities as slag
Explanation: Limestone is added to the blast furnace to remove impurities. It decomposes to form calcium oxide, which then reacts with silica (the main impurity) to form slag.
10. The extraction of copper by the Bessemer process involves the oxidation of:
- A) Sulphur and iron impurities
- B) Carbon
- C) Silicon
- D) Calcium carbonate
Answer: A) Sulphur and iron impurities
Explanation: In the Bessemer process for copper extraction, air is blown through molten copper matte (a mixture of copper and iron sulphides). The air oxidizes the sulphur and iron impurities, which are then removed as slag or gas (as sulphur dioxide).
11. Which of the following reactions occurs during the calcination process?
- A) 2ZnS+3O2→2ZnO+2SO2
- B) CaCO3→CaO+CO2
- C) 2FeS+3O2→2FeO+2SO2
- D) Cu2S+O2→Cu2O+SO2
Answer: B) CaCO3→CaO+CO2
Explanation: Calcination is the process of heating an ore in the absence or limited supply of air to remove volatile impurities. For example, in the calcination of limestone, calcium carbonate decomposes to form calcium oxide and carbon dioxide.
12. In the blast furnace, which zone is the hottest?
- A) Combustion zone
- B) Fusion zone
- C) Reduction zone
- D) Slag formation zone
Answer: A) Combustion zone
Explanation: The combustion zone, located at the bottom of the blast furnace, is the hottest part, where coke burns in the presence of oxygen to produce carbon dioxide and heat. This heat drives the other reactions occurring in the furnace.
13. Which of the following metals is extracted by using the electrolysis of its molten ore?
- A) Iron
- B) Copper
- C) Aluminium
- D) Zinc
Answer: C) Aluminium
Explanation: Aluminium is extracted by the electrolysis of molten alumina (Al2O3Al2O3) dissolved in molten cryolite. This method is used because aluminium is highly reactive, and it cannot be reduced by carbon like iron.
14. During the extraction of copper from copper matte, FeS is converted to FeO by:
- A) Roasting
- B) Smelting
- C) Calcination
- D) Electrolysis
Answer: A) Roasting
Explanation: Roasting involves heating copper matte in the presence of oxygen, during which iron sulphide (FeS) is oxidized to iron oxide (FeO) and sulphur dioxide gas is released.
15. Which of the following is removed as slag in the extraction of iron from its ore?
- A) Calcium silicate
- B) Iron silicate
- C) Ferric oxide
- D) Calcium oxide
Answer: A) Calcium silicate
Explanation: In the blast furnace, silica impurities in the ore react with lime (CaO) to form calcium silicate (CaSiO3), which is removed as slag.
16. The Ellingham diagram is used to predict the feasibility of:
- A) Roasting of ores
- B) Reduction of metal oxides
- C) Electrolysis of metals
- D) Leaching of ores
Answer: B) Reduction of metal oxides
Explanation: The Ellingham diagram is a graphical representation that helps predict the thermodynamic feasibility of the reduction of metal oxides by comparing the free energy changes of reactions at different temperatures.
17. In the extraction of copper by the electrorefining method, the impure copper is used as:
- A) Cathode
- B) Anode
- C) Electrolyte
- D) None of the above
Answer: B) Anode
Explanation: During electrorefining of copper, the impure copper is made the anode, and pure copper is deposited at the cathode. Impurities like silver and gold settle down as anode mud.
18. Which of the following is a primary source of iron in the blast furnace?
- A) Hematite
- B) Bauxite
- C) Calamine
- D) Malachite
Answer: A) Hematite
Explanation: Hematite (Fe2O3) is the primary ore of iron used in the blast furnace for extracting iron. It is reduced to iron by carbon monoxide in the furnace.
19. In the Bayer process, the major impurity present in bauxite is removed by:
- A) Heating with carbon
- B) Treating with sodium hydroxide
- C) Electrolysis
- D) Froth flotation
Answer: B) Treating with sodium hydroxide
Explanation: In the Bayer process, bauxite is treated with sodium hydroxide, which dissolves alumina, leaving behind impurities such as iron oxides and silica as insoluble residues.
20. Which of the following is used as a flux in the extraction of iron?
- A) Silica
- B) Limestone
- C) Alumina
- D) Sulphur dioxide
Answer: B) Limestone
Explanation: Limestone (calcium carbonate) is used as a flux in the extraction of iron. It decomposes to form calcium oxide, which then reacts with silica impurities to form slag.
21. The Hall-Heroult process is used for the extraction of:
- A) Copper
- B) Zinc
- C) Aluminium
- D) Iron
Answer: C) Aluminium
Explanation: The Hall-Héroult process is the electrolytic method used for extracting aluminium from alumina. In this process, molten alumina is dissolved in molten cryolite and electrolyzed to obtain pure aluminium.
22. Which of the following reactions occurs in the blast furnace during the extraction of iron?
- A) C+O2→CO2
- B) CO2+C→2CO
- C) Fe2O3+3CO→2Fe+3CO2
- D) All of the above
Answer: D) All of the above
Explanation: All of these reactions occur in the blast furnace. Coke burns in oxygen to form carbon dioxide, which then reacts with more coke to form carbon monoxide, which finally reduces iron ore to iron.
23. Which of the following metals is extracted from its ore by the froth flotation method?
- A) Iron
- B) Aluminium
- C) Copper
- D) Zinc
Answer: C) Copper
Explanation: Froth flotation is used for the concentration of copper sulphide ores. The ore is crushed, mixed with water, and then treated with reagents to make the copper sulphide particles hydrophobic, so they attach to air bubbles and float.
24. The removal of sulphur from the molten metal in the extraction of copper is done by:
- A) Oxidation
- B) Reduction
- C) Leaching
- D) Electrolysis
Answer: A) Oxidation
Explanation: Sulphur is removed during the extraction of copper by oxidation. Sulphur combines with oxygen to form sulphur dioxide gas, which escapes.
25. Which of the following metals is not extracted using carbon as a reducing agent?
- A) Iron
- B) Copper
- C) Aluminium
- D) Zinc
Answer: C) Aluminium
Explanation: Aluminium is a highly electropositive metal, so it is extracted by electrolysis, not by reduction with carbon. Carbon is not a strong enough reducing agent to reduce aluminium oxide to aluminium.
26. In the blast furnace, the reducing agent responsible for converting iron oxide to iron is:
- A) Carbon
- B) Carbon monoxide
- C) Hydrogen
- D) Sodium
Answer: B) Carbon monoxide
Explanation: Carbon monoxide is the primary reducing agent in the blast furnace that reduces iron oxide to iron: Fe2O3+3CO→2Fe+3CO2
27. In the metallurgy of copper, the compound formed when copper pyrite (CuFeS2) is heated in the absence of air is:
- A) Copper sulphate
- B) Copper oxide
- C) Matte (Cu_2S and FeS)
- D) Copper metal
Answer: C) Matte (Cu_2S and FeS)
Explanation: When copper pyrite is heated in the absence of air, it forms matte, which is a mixture of copper(I) sulphide (Cu2S) and iron sulphide (FeS).
28. Which of the following processes is employed in the extraction of iron from iron ore?
- A) Smelting
- B) Electrolysis
- C) Froth flotation
- D) Leaching
Answer: A) Smelting
Explanation: Smelting is the process used to extract iron from its ore in a blast furnace. In this process, iron ore is heated with a reducing agent like carbon to obtain the metal.
29. In the extraction of iron, slag is formed by the reaction of:
- A) Iron oxide and silica
- B) Silica and calcium oxide
- C) Hematite and carbon monoxide
- D) Coke and iron oxide
Answer: B) Silica and calcium oxide
Explanation: Slag is formed by the reaction of silica (an impurity in the ore) with calcium oxide (obtained from limestone) to form calcium silicate: CaO+SiO2→CaSiO3CaO+SiO2→CaSiO3
30. Which of the following ores is concentrated by froth flotation?
- A) Bauxite
- B) Hematite
- C) Chalcopyrite
- D) Magnetite
Answer: C) Chalcopyrite
Explanation: Chalcopyrite (CuFeS2) is a sulphide ore of copper and is concentrated by froth flotation, a method specifically used for sulphide ores.
31. In the extraction of iron, carbon acts as:
- A) Oxidizing agent
- B) Reducing agent
- C) Flux
- D) Neutralizer
Answer: B) Reducing agent
Explanation: Carbon, in the form of coke, acts as a reducing agent in the blast furnace. It reduces iron oxide to iron: Fe2O3+3C→2Fe+3CO2
32. The slag formed during the extraction of iron in a blast furnace is:
- A) Ferrous oxide
- B) Calcium silicate
- C) Ferric oxide
- D) Iron silicate
Answer: B) Calcium silicate
Explanation: The slag in the blast furnace is calcium silicate (CaSiO3), formed by the reaction of calcium oxide (from limestone) with silica.
33. In the extraction of iron from haematite, the charge used in the blast furnace consists of:
- A) Haematite, coke, and limestone
- B) Magnetite, coke, and sand
- C) Iron scrap and limestone
- D) Iron oxide and aluminium
Answer: A) Haematite, coke, and limestone
Explanation: The charge in a blast furnace includes haematite (Fe2O3), coke (carbon source), and limestone (flux) to extract iron.
34. The copper obtained from copper pyrites is known as:
- A) Blister copper
- B) Matte
- C) Pure copper
- D) Copper oxide
Answer: A) Blister copper
Explanation: Blister copper is the form of copper obtained after smelting copper pyrites. It contains impurities and has a blistered appearance due to escaping sulfur dioxide gas.
35. The compound of iron which is most suitable for extraction of iron is:
- A) Ferric chloride
- B) Ferrous sulphate
- C) Haematite
- D) Iron pyrite
Answer: C) Haematite
Explanation: Haematite (Fe2O3) is the most suitable ore for the extraction of iron. It is the principal source of iron in the blast furnace process.
36. Which of the following metals is purified by distillation?
- A) Aluminium
- B) Copper
- C) Zinc
- D) Iron
Answer: C) Zinc
Explanation: Zinc has a relatively low boiling point compared to other metals. It can be purified by distillation after smelting.
37. Which of the following is not true for roasting?
- A) Roasting involves heating the ore in the presence of air
- B) Sulphide ores are generally roasted
- C) Roasting converts sulphide ores to oxides
- D) Roasting is used for carbonate ores
Answer: D) Roasting is used for carbonate ores
Explanation: Roasting is generally used for sulphide ores, not carbonate ores. Carbonate ores are typically subjected to calcination.
38. In the extraction of copper, which material is added to remove the impurity of iron?
- A) Lime
- B) Coke
- C) Silica
- D) Charcoal
Answer: C) Silica
Explanation: Silica is added to remove the impurity of iron in the form of iron silicate (slag) during copper extraction.
39. In the metallurgy of iron, limestone is added to the furnace to:
- A) Reduce iron oxide to iron
- B) Act as a flux
- C) Act as an oxidizing agent
- D) Remove impurities
Answer: B) Act as a flux
Explanation: Limestone acts as a flux in the blast furnace, which combines with impurities to form slag (calcium silicate).
40. Which of the following is not used as a flux in metallurgy?
- A) Silica
- B) Lime
- C) Cryolite
- D) Coke
Answer: D) Coke
Explanation: Coke is a reducing agent, not a flux. Fluxes like silica, lime, and cryolite are used to remove impurities.
41. Which metal is extracted from its ore using the Mond process?
- A) Copper
- B) Iron
- C) Nickel
- D) Zinc
Answer: C) Nickel
Explanation: The Mond process is used to extract and purify nickel. In this process, nickel reacts with carbon monoxide to form nickel carbonyl, which decomposes to yield pure nickel.
42. During the roasting of pyrite (FeS2), the following gas is produced:
- A) Carbon dioxide
- B) Sulphur dioxide
- C) Hydrogen sulphide
- D) Oxygen
Answer: B) Sulphur dioxide
Explanation: During the roasting of pyrite, iron sulphide (FeS2) reacts with oxygen to produce sulphur dioxide (SO2) and iron oxide.
43. The process of leaching involves:
- A) Heating of ore in the presence of oxygen
- B) Heating the ore with reducing agent
- C) Treating the ore with suitable reagent to form a soluble compound
- D) Electrolytic reduction of ore
Answer: C) Treating the ore with suitable reagent to form a soluble compound
Explanation: Leaching is a hydrometallurgical process where the ore is treated with a reagent that dissolves the desired metal, forming a soluble compound, which can then be recovered.
44. Which of the following processes is used to extract metals from sulphide ores?
- A) Roasting
- B) Calcination
- C) Distillation
- D) Electrolysis
Answer: A) Roasting
Explanation: Roasting is used to extract metals from sulphide ores by heating them in the presence of air to convert the sulphides into oxides.
45. The impurities left behind after electrorefining of copper are known as:
- A) Anode mud
- B) Cathode deposit
- C) Slag
- D) Dross
Answer: A) Anode mud
Explanation: During the electrorefining of copper, impurities such as silver and gold settle at the bottom of the cell as anode mud.
46. Which of the following metals is extracted by the auto-reduction process?
- A) Zinc
- B) Copper
- C) Aluminium
- D) Iron
Answer: B) Copper
Explanation: Copper is extracted by auto-reduction (self-reduction), where Cu2S is converted to copper metal by reaction with oxygen. This occurs during the final stages of copper extraction in the Bessemer converter.
47. The electrochemical method used for refining copper is known as:
- A) Electroplating
- B) Electrolysis
- C) Electrorefining
- D) Electrowinning
Answer: C) Electrorefining
Explanation: Electrorefining is used for the purification of copper. Impure copper is made the anode, and pure copper is deposited at the cathode.
48. In the metallurgy of iron, the function of coke is to:
- A) Act as a reducing agent
- B) Act as an oxidizing agent
- C) Remove impurities
- D) Form slag
Answer: A) Act as a reducing agent
Explanation: Coke is used in the blast furnace as a reducing agent to convert iron oxides into iron metal.
49. During the extraction of copper, which step involves the use of SiO2?
- A) Smelting
- B) Electrorefining
- C) Roasting
- D) Reduction
Answer: A) Smelting
Explanation: During smelting, silica (SiO2) is added as a flux to remove iron impurities in the form of iron silicate (slag).
50. The metal obtained after smelting iron ore in the blast furnace is called:
- A) Pig iron
- B) Wrought iron
- C) Steel
- D) Cast iron
Answer: A) Pig iron
Explanation: Pig iron is the first product obtained from smelting iron ore in a blast furnace. It contains high carbon content and other impurities.
51. In the extraction of copper, the electrolyte used during electrorefining is:
- A) Sodium chloride solution
- B) Copper sulphate solution
- C) Ferrous sulphate solution
- D) Zinc chloride solution
Answer: B) Copper sulphate solution
Explanation: During electrorefining, copper sulphate solution is used as the electrolyte, and pure copper is deposited at the cathode.
52. Which of the following is not true about the blast furnace?
- A) It is used for the extraction of iron
- B) It operates at high temperatures
- C) Carbon monoxide is the reducing agent
- D) It is used to refine iron to produce steel
Answer: D) It is used to refine iron to produce steel
Explanation: The blast furnace is used to extract iron from its ores, not to refine it into steel. Steelmaking is a separate process involving the removal of carbon and other impurities from pig iron.
53. In the extraction of copper, which gas is produced during the roasting of copper pyrite?
- A) Oxygen
- B) Nitrogen
- C) Sulphur dioxide
- D) Carbon dioxide
Answer: C) Sulphur dioxide
Explanation: During the roasting of copper pyrite (CuFeS2), sulphur is oxidized to sulphur dioxide (SO2), which escapes as a gas.
54. The temperature at the bottom of the blast furnace during the extraction of iron is approximately:
- A) 200°C
- B) 700°C
- C) 1200°C
- D) 1900°C
Answer: D) 1900°C
Explanation: The temperature at the bottom of the blast furnace, in the combustion zone, can reach around 1900°C, which is necessary for the reduction of iron ores.
55. Which of the following processes is used for the concentration of bauxite ore?
- A) Leaching
- B) Froth flotation
- C) Smelting
- D) Distillation
Answer: A) Leaching
Explanation: In the Bayer process, bauxite ore is concentrated by leaching, where alumina is dissolved in sodium hydroxide and separated from impurities.
56. Which reducing agent is used in the extraction of iron from haematite in the blast furnace?
- A) Hydrogen
- B) Carbon
- C) Carbon monoxide
- D) Aluminium
Answer: C) Carbon monoxide
Explanation: Carbon monoxide is the reducing agent that reduces iron ore (haematite) to iron in the blast furnace.
57. In the extraction of copper from copper pyrite, which of the following is the purpose of the converter?
- A) Reduction of copper oxide
- B) Removal of sulphur and iron as slag
- C) Concentration of ore
- D) Electrolytic refining
Answer: B) Removal of sulphur and iron as slag
Explanation: In the Bessemer converter, sulphur and iron are removed from copper matte as sulphur dioxide gas and iron silicate slag, respectively.
58. The chief ore of aluminium is:
- A) Magnetite
- B) Bauxite
- C) Calamine
- D) Cinnabar
Answer: B) Bauxite
Explanation: Bauxite (Al2O3⋅2H2O) is the chief ore of aluminium. It is processed through the Bayer process to extract alumina, which is then reduced by electrolysis to produce aluminium.
59. Which of the following metals is obtained by the electrolytic reduction of alumina?
- A) Zinc
- B) Aluminium
- C) Iron
- D) Copper
Answer: B) Aluminium
Explanation: Aluminium is obtained by the electrolytic reduction of alumina (Al2O3) in the Hall-Héroult process. Alumina is dissolved in molten cryolite and electrolyzed to produce aluminium.
60. In the extraction of iron, carbon monoxide acts as a reducing agent in the reaction:
- A) Fe2O3+3CO→2Fe+3CO2
- B) Fe2O3+3C→2Fe+3CO2
- C) FeO+C→Fe+CO
- D) FeO+CO2→Fe+CO
Answer: A) Fe2O3+3CO→2Fe+3CO2
Explanation: Carbon monoxide reduces haematite (Fe2O3) to iron in the blast furnace, producing carbon dioxide as a byproduct.
61. Which metal is extracted by the Bayer process?
- A) Copper
- B) Zinc
- C) Aluminium
- D) Iron
Answer: C) Aluminium
Explanation: The Bayer process is used to extract alumina from bauxite ore, which is further reduced to aluminium metal through electrolysis.
62. The reducing agent used in the thermite process for the extraction of metals is:
- A) Carbon
- B) Sodium
- C) Aluminium
- D) Magnesium
Answer: C) Aluminium
Explanation: In the thermite process, aluminium powder is used as a reducing agent to extract metals like iron from their oxides by reducing them at high temperatures.
63. During the smelting of copper, which material is added to remove iron impurities?
- A) Sodium carbonate
- B) Lime
- C) Silica
- D) Carbon
Answer: C) Silica
Explanation: Silica (SiO2) is added during smelting to remove iron impurities as iron silicate (FeSiO3) slag.
64. The major impurity present in bauxite ore is:
- A) Silica
- B) Iron oxide
- C) Calcium oxide
- D) Zinc oxide
Answer: B) Iron oxide
Explanation: The major impurity present in bauxite is iron oxide, which is removed during the Bayer process through leaching.
65. Which of the following processes is used to purify blister copper?
- A) Roasting
- B) Smelting
- C) Electrorefining
- D) Leaching
Answer: C) Electrorefining
Explanation: Electrorefining is used to purify blister copper. In this process, impure copper is used as the anode, and pure copper is deposited at the cathode.
66. The chemical reaction occurring during the extraction of iron from its ore in the blast furnace is:
- A) Fe2O3+3CO→2Fe+3CO2
- B) Fe2O3+3C→2Fe+3CO2
- C) Fe2O3+2Al→2Fe+Al2O3
- D) FeO+C→Fe+CO
Answer: A) Fe2O3+3CO→2Fe+3CO2
Explanation: In the blast furnace, carbon monoxide reduces iron oxide (Fe2O3) to iron while forming carbon dioxide.
67. In the extraction of copper from copper pyrites, the slag formed is:
- A) FeSiO3
- B) CuSiO3
- C) CaSiO3
- D) SiO2
Answer: A) FeSiO3
Explanation: During the extraction of copper, silica is added as a flux to remove iron impurities as iron silicate (FeSiO3) slag.
68. The Hall-Héroult process is used for the extraction of:
- A) Copper
- B) Aluminium
- C) Zinc
- D) Iron
Answer: B) Aluminium
Explanation: The Hall-Héroult process is an electrolytic process used for the extraction of aluminium from alumina dissolved in molten cryolite.
69. In the extraction of iron, the reaction of coke with oxygen in the combustion zone produces:
- A) Carbon dioxide
- B) Carbon monoxide
- C) Oxygen
- D) Nitrogen
Answer: A) Carbon dioxide
Explanation: In the combustion zone of the blast furnace, coke reacts with oxygen to produce carbon dioxide, releasing heat: C+O2→CO2
70. In the extraction of copper, the Bessemer converter is used to:
- A) Roast the ore
- B) Refine the copper
- C) Remove sulphur and iron impurities
- D) Electrolyze the copper
Answer: C) Remove sulphur and iron impurities
Explanation: The Bessemer converter is used to remove sulphur and iron from copper matte by converting them into gases and slag, respectively.
71. Which of the following is not a part of the blast furnace process for extracting iron?
- A) Roasting
- B) Reduction
- C) Smelting
- D) Calcination
Answer: D) Calcination
Explanation: Calcination is not part of the blast furnace process. It involves heating ores in the absence of air, while the blast furnace involves reduction and smelting.
72. In the extraction of copper from copper pyrites, the matte contains:
- A) Copper sulphide and iron sulphide
- B) Copper oxide and iron oxide
- C) Copper and zinc
- D) Copper oxide and carbon
Answer: A) Copper sulphide and iron sulphide
Explanation: The matte formed in copper extraction consists of copper sulphide (Cu2S) and iron sulphide (FeS).
73. In the blast furnace, which of the following acts as a flux?
- A) Coke
- B) Silica
- C) Calcium oxide
- D) Alumina
Answer: C) Calcium oxide
Explanation: Calcium oxide (lime) is used as a flux in the blast furnace. It reacts with silica impurities to form calcium silicate (slag).
74. The role of cryolite in the electrolytic extraction of aluminium is to:
- A) Increase the electrical conductivity of the solution
- B) Lower the melting point of alumina
- C) Act as a reducing agent
- D) Remove impurities from the ore
Answer: B) Lower the melting point of alumina
Explanation: Cryolite is added to lower the melting point of alumina and increase the efficiency of the electrolytic extraction of aluminium.
75. The major impurity in iron extracted from the blast furnace is:
- A) Carbon
- B) Silica
- C) Sulphur
- D) Phosphorus
Answer: A) Carbon
Explanation: Pig iron, extracted from the blast furnace, contains a high percentage of carbon as the major impurity, making it brittle.
76. Which metal is obtained by the electrolysis of fused bauxite?
- A) Copper
- B) Aluminium
- C) Iron
- D) Zinc
Answer: B) Aluminium
Explanation: Aluminium is obtained by the electrolysis of fused alumina (extracted from bauxite) in the Hall-Héroult process.
77. Which of the following metals is refined by liquation?
- A) Zinc
- B) Lead
- C) Copper
- D) Aluminium
Answer: B) Lead
Explanation: Liquation is used for refining metals like lead and tin, where impurities have a higher melting point than the metal.
78. The ore haematite is an important source of:
- A) Aluminium
- B) Copper
- C) Iron
- D) Zinc
Answer: C) Iron
Explanation: Haematite (Fe2O3) is an important ore of iron, used as the primary source of iron in the blast furnace process.
79. Which of the following is not an ore of copper?
- A) Chalcopyrite
- B) Malachite
- C) Cuprite
- D) Siderite
Answer: D) Siderite
Explanation: Siderite (FeCO3) is an ore of iron, not copper. The other three are copper ores.
80. In the extraction of iron, the limestone added to the blast furnace:
- A) Acts as a flux
- B) Acts as a reducing agent
- C) Reduces the iron oxide to iron
- D) Produces carbon monoxide
Answer: A) Acts as a flux
Explanation: Limestone decomposes to form calcium oxide, which acts as a flux to remove silica impurities by forming slag.
81. The Mond process is used for refining:
- A) Zinc
- B) Nickel
- C) Aluminium
- D) Copper
Answer: B) Nickel
Explanation: The Mond process is used for refining nickel. In this process, nickel reacts with carbon monoxide to form nickel carbonyl, which decomposes to yield pure nickel.
82. In the extraction of copper, the matte is further treated to obtain:
- A) Blister copper
- B) Pure copper
- C) Copper sulphate
- D) Copper oxide
Answer: A) Blister copper
Explanation: Matte, which contains Cu2SCu2S, is further treated by blowing air through it to produce blister copper, which contains around 98% pure copper.
83. Which of the following methods is used to extract metals from sulphide ores?
- A) Roasting
- B) Electrolysis
- C) Smelting
- D) Leaching
Answer: A) Roasting
Explanation: Roasting is the process of heating sulphide ores in the presence of oxygen to convert them to oxides, which can then be reduced to metal.
84. In the Bayer process, the impurity removed from bauxite ore is:
- A) Iron oxide
- B) Silicon dioxide
- C) Zinc oxide
- D) Lead oxide
Answer: A) Iron oxide
Explanation: In the Bayer process, iron oxide is removed as an impurity from bauxite ore to obtain pure alumina, which is further processed to produce aluminium.
85. Which of the following metals is not extracted by the smelting process?
- A) Zinc
- B) Aluminium
- C) Copper
- D) Iron
Answer: B) Aluminium
Explanation: Aluminium is not extracted by smelting. It is extracted by the electrolytic reduction of alumina in the Hall-Héroult process.
86. The metal extracted using the cyanide process is:
- A) Copper
- B) Aluminium
- C) Zinc
- D) Gold
Answer: D) Gold
Explanation: The cyanide process (or MacArthur-Forrest process) is used for the extraction of gold and silver from their ores.
87. In the extraction of iron, what is the role of coke in the blast furnace?
- A) It acts as a flux
- B) It acts as a reducing agent
- C) It removes impurities
- D) It reacts with iron oxide
Answer: B) It acts as a reducing agent
Explanation: Coke is used in the blast furnace as a reducing agent to convert iron oxides into iron by producing carbon monoxide.
88. Which of the following reactions occurs during the reduction of iron ore in a blast furnace?
- A) Fe2O3+3C→2Fe+3CO
- B) FeO+CO→Fe+CO2
- C) Fe2O3+C→2Fe+CO2
- D) Fe+C→FeC
Answer: B) FeO+CO→Fe+CO2
Explanation: In the blast furnace, carbon monoxide reduces iron oxide (FeO to iron, producing carbon dioxide.
89. Which of the following metals is extracted using the electrolytic reduction of its oxide?
- A) Copper
- B) Iron
- C) Aluminium
- D) Lead
Answer: C) Aluminium
Explanation: Aluminium is extracted from its oxide (alumina) using electrolytic reduction in the Hall-Héroult process.
90. Which of the following is the main impurity removed in the extraction of copper by the Bessemer process?
- A) Zinc
- B) Iron
- C) Aluminium
- D) Sulphur
Answer: B) Iron
Explanation: In the Bessemer process, iron is removed as slag (FeSiO3) by reacting with silica during copper extraction.
91. In the extraction of zinc from zinc blende, the ore is first concentrated by:
- A) Roasting
- B) Smelting
- C) Froth flotation
- D) Calcination
Answer: C) Froth flotation
Explanation: Zinc blende (ZnS) is concentrated using froth flotation before being roasted to convert it to zinc oxide for further processing.
92. The method used to refine metals like tin and lead is:
- A) Electrolysis
- B) Liquation
- C) Zone refining
- D) Froth flotation
Answer: B) Liquation
Explanation: Liquation is used to refine metals like tin and lead, which have low melting points, by melting and separating impurities.
93. The slag formed during the extraction of iron in the blast furnace is:
- A) SiO2
- B) FeSiO3
- C) CaSiO3
- D) Fe2O3
Answer: C) CaSiO3
Explanation: During the extraction of iron, calcium oxide reacts with silica to form calcium silicate (CaSiO3), which is removed as slag.
94. In the extraction of aluminium, the substance that lowers the melting point of alumina is:
- A) Sodium hydroxide
- B) Cryolite
- C) Calcium oxide
- D) Magnesium oxide
Answer: B) Cryolite
Explanation: Cryolite (Na3AlF6) is added to alumina to lower its melting point during the electrolytic extraction of aluminium.
95. The gas released during the roasting of zinc blende is:
- A) Carbon dioxide
- B) Sulphur dioxide
- C) Oxygen
- D) Nitrogen
Answer: B) Sulphur dioxide
Explanation: During roasting, zinc sulphide (ZnS) is heated in the presence of oxygen, releasing sulphur dioxide (SO2) gas.
96. Which of the following metals is obtained by the carbon reduction of its oxide?
- A) Aluminium
- B) Zinc
- C) Magnesium
- D) Copper
Answer: B) Zinc
Explanation: Zinc oxide is reduced by carbon in a furnace to obtain zinc metal in the extraction process.
97. In the Hall-Héroult process, the electrolyte used is:
- A) Sodium hydroxide
- B) Cryolite and alumina
- C) Zinc chloride
- D) Copper sulphate
Answer: B) Cryolite and alumina
Explanation: In the Hall-Héroult process, alumina (Al2O3) is dissolved in molten cryolite (Na3AlF6) to act as the electrolyte for the extraction of aluminium.
98. In the extraction of iron, carbon monoxide is produced by:
- A) The combustion of carbon
- B) The reaction of carbon with oxygen
- C) The reduction of carbon dioxide by carbon
- D) The reaction of carbon monoxide with iron ore
Answer: C) The reduction of carbon dioxide by carbon
Explanation: Carbon dioxide is reduced to carbon monoxide by reacting with coke (carbon) in the blast furnace.
99. The flux used in the smelting of copper to remove iron impurities is:
- A) Lime
- B) Silica
- C) Carbon
- D) Sodium carbonate
Answer: B) Silica
Explanation: Silica (SiO2) is used as a flux during the smelting of copper to remove iron as iron silicate slag.
100. The final product obtained after the electrorefining of copper is:
- A) Blister copper
- B) Matte
- C) Pure copper
- D) Copper oxide
Answer: C) Pure copper
Explanation: Electrorefining of copper results in the deposition of pure copper at the cathode, while impurities remain in the electrolyte or form anode sludge.
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