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.
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