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.
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