Q.1 Which of the following methods is commonly used for the extraction of aluminium?
Electrolysis of alumina
Reduction of aluminium oxide with carbon
Distillation
Hydrometallurgy
Explanation - Aluminium is extracted from bauxite ore by the electrolysis of alumina (Al2O3) dissolved in molten cryolite.
Correct answer is: Electrolysis of alumina
Q.2 Which process is used for refining copper on an industrial scale?
Zone refining
Electrolytic refining
Distillation
Fractional crystallization
Explanation - Copper is refined by electrolytic refining where impure copper acts as an anode and pure copper gets deposited at the cathode.
Correct answer is: Electrolytic refining
Q.3 Which of the following is a noble metal that is usually found in nature in free state?
Copper
Gold
Zinc
Iron
Explanation - Gold is chemically inert and does not easily form compounds, so it is often found in its native (free) state.
Correct answer is: Gold
Q.4 Froth flotation is a method used for the concentration of which type of ores?
Sulphide ores
Oxide ores
Native metals
Carbonate ores
Explanation - Froth flotation separates hydrophobic sulphide ores from gangue using chemicals and air bubbles.
Correct answer is: Sulphide ores
Q.5 Which metal is obtained by the Mond process?
Nickel
Iron
Zinc
Lead
Explanation - The Mond process purifies nickel by forming volatile nickel carbonyl which is decomposed to yield pure nickel.
Correct answer is: Nickel
Q.6 Calcination is a process primarily used to remove:
Moisture
Impurities by heating in absence of air
Sulphur
All of the above
Explanation - Calcination involves heating ores below their melting point to remove moisture and volatile impurities.
Correct answer is: Moisture
Q.7 Which of the following metals is extracted by the Kroll process?
Titanium
Aluminium
Copper
Zinc
Explanation - Titanium is extracted from TiCl4 by reduction with magnesium in the Kroll process.
Correct answer is: Titanium
Q.8 Which is the major impurity removed during the refining of lead?
Silver
Arsenic
Iron
All of the above
Explanation - Lead ores contain impurities like silver, arsenic, and iron, which are removed by cupellation or other refining methods.
Correct answer is: All of the above
Q.9 What is the main purpose of roasting an ore?
To oxidize sulphide ores
To remove moisture
To reduce metal oxides
To increase melting point
Explanation - Roasting converts sulphide ores into oxides by heating in presence of oxygen, preparing them for reduction.
Correct answer is: To oxidize sulphide ores
Q.10 Which metal is extracted by the electrolysis of its fused chloride?
Sodium
Copper
Iron
Lead
Explanation - Sodium is extracted by electrolysis of molten sodium chloride (Downs process) because carbon reduction is not possible.
Correct answer is: Sodium
Q.11 Which process is used to obtain zinc from its ore?
Electrolysis of molten ZnO
Distillation of Zn
Leaching followed by precipitation
All of the above
Explanation - Zinc is obtained by reducing zinc oxide with carbon and distilling the zinc vapor for collection.
Correct answer is: Distillation of Zn
Q.12 Which of the following ores is concentrated by magnetic separation?
Hematite
Magnetite
Bauxite
Galena
Explanation - Magnetite (Fe3O4) is magnetic and can be separated from gangue using magnets.
Correct answer is: Magnetite
Q.13 Which metal is obtained by reduction of its oxide with hydrogen gas?
Tungsten
Copper
Iron
Aluminium
Explanation - Tungsten oxide is reduced with hydrogen at high temperatures to produce pure tungsten.
Correct answer is: Tungsten
Q.14 Which of the following is a common flux used in metallurgy?
CaO
NaCl
HCl
H2SO4
Explanation - Calcium oxide (lime) is used as a flux to remove acidic impurities from the ore during smelting.
Correct answer is: CaO
Q.15 Which method is used for the extraction of copper from low-grade ores?
Hydrometallurgy
Pyrometallurgy
Electrolytic refining
All of the above
Explanation - Low-grade copper ores are treated by leaching with appropriate solutions and recovery of copper by cementation or electrolysis.
Correct answer is: Hydrometallurgy
Q.16 Which process is used to purify silver?
Electrolytic refining
Cupellation
Distillation
Zone refining
Explanation - Silver is refined electrolytically using a silver anode, nitric acid solution, and pure silver deposition at the cathode.
Correct answer is: Electrolytic refining
Q.17 Which of the following metals is generally obtained by reduction with carbon?
Iron
Aluminium
Titanium
Magnesium
Explanation - Iron is extracted from hematite (Fe2O3) by reduction with carbon in a blast furnace.
Correct answer is: Iron
Q.18 Which of the following is a reason for using cryolite in aluminium extraction?
To lower melting point of alumina
To increase conductivity
To prevent alumina decomposition
All of the above
Explanation - Cryolite lowers the melting point of alumina, improves conductivity, and stabilizes it during electrolysis.
Correct answer is: All of the above
Q.19 Which of the following metals is extracted from a carbonate ore by calcination?
Zinc
Iron
Aluminium
Copper
Explanation - Zinc carbonate ores (like ZnCO3) are heated to decompose into zinc oxide before reduction.
Correct answer is: Zinc
Q.20 Which of the following metals is refined by the Van Arkel method?
Titanium
Copper
Zinc
Gold
Explanation - Van Arkel method purifies titanium and zirconium by forming volatile tetraiodides and decomposing them on hot filaments.
Correct answer is: Titanium
Q.21 Which of the following ores is concentrated by levigation?
Heavy mineral ores
Magnetite
Bauxite
Galena
Explanation - Levigation separates lighter gangue particles from heavier ore particles using flowing water.
Correct answer is: Heavy mineral ores
Q.22 Which of the following metals is obtained by electrolytic reduction in molten state?
Aluminium
Copper
Iron
Lead
Explanation - Aluminium is extracted by the Hall-Héroult process, which electrolytically reduces alumina dissolved in molten cryolite.
Correct answer is: Aluminium
Q.23 Which of the following is the main principle behind zone refining?
Differential solubility
Differential melting points
Electrolysis
Froth flotation
Explanation - Zone refining purifies metals by moving a molten zone along a solid rod, segregating impurities based on melting point differences.
Correct answer is: Differential melting points
Q.24 Which metal is extracted by reduction of its oxide using aluminium (thermite process)?
Iron
Copper
Zinc
Aluminium
Explanation - Thermite process reduces iron oxide to iron using aluminium powder as a reducing agent, producing molten iron.
Correct answer is: Iron
Q.25 Which of the following metals is extracted by the electrolytic reduction of molten chloride in a Downs cell?
Sodium
Potassium
Calcium
Magnesium
Explanation - In the Downs process, molten NaCl is electrolyzed to produce sodium metal and chlorine gas.
Correct answer is: Sodium