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.
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