Class 12 Chemistry MCQ – General Principles and Processes of Isolation of Elements

1. Which of the following is an ore of iron?

a) Bauxite
b) Galena
c) Hematite
d) Cinnabar

Answer:

c) Hematite

Explanation:

Hematite (Fe2O3) is an iron ore, while the other options are ores of different metals.

2. The process in which ore is heated in the absence of air is known as:

a) Calcination
b) Roasting
c) Smelting
d) Refining

Answer:

a) Calcination

Explanation:

Calcination is the process of heating an ore in the absence of air to drive away moisture and volatile impurities.

3. Which method is used for refining of noble metals like gold and silver?

a) Electrolytic refining
b) Zone refining
c) Vapor-phase refining
d) Liquation

Answer:

a) Electrolytic refining

Explanation:

Noble metals such as gold and silver are refined using the electrolytic refining method.

4. Froth flotation is used for the concentration of:

a) Oxide ores
b) Carbonate ores
c) Sulphide ores
d) Halide ores

Answer:

c) Sulphide ores

Explanation:

The froth flotation process is mainly used for the concentration of sulphide ores.

5. Which of the following ores is best concentrated by leaching?

a) Copper pyrite
b) Bauxite
c) Magnetite
d) Hematite

Answer:

b) Bauxite

Explanation:

Bauxite, an ore of aluminum, is best concentrated by the leaching process using sodium hydroxide.

6. The process used for the extraction of metals in the middle of the activity series, such as iron, is:

a) Electrolysis
b) Carbon reduction
c) Hydrometallurgy
d) Pyrometallurgy

Answer:

b) Carbon reduction

Explanation:

Metals in the middle of the activity series like iron are extracted by reduction with carbon.

7. Which of the following metals is obtained by the electrolysis of its molten chloride?

a) Iron
b) Aluminum
c) Sodium
d) Copper

Answer:

c) Sodium

Explanation:

Sodium is obtained by the electrolysis of its molten chloride (NaCl).

8. The role of silica in the metallurgy of copper is to:

a) Act as a flux
b) Decrease the melting point
c) Remove the acidic impurities
d) Oxidize the ore

Answer:

a) Act as a flux

Explanation:

In the metallurgy of copper, silica acts as a flux and combines with acidic impurities to form a slag.

9. Which of the following is a flux in the extraction of iron from hematite?

a) Limestone
b) Silica
c) Coke
d) Zinc

Answer:

a) Limestone

Explanation:

Limestone (CaCO3) acts as a flux in the extraction of iron from hematite.

10. The method used for refining zinc is:

a) Electrolytic refining
b) Distillation
c) Zone refining
d) Froth flotation

Answer:

b) Distillation

Explanation:

Zinc is refined using distillation as it has a low boiling point.

11. In the extraction of chlorine by electrolysis of brine, which of the following gases is released at the anode?

a) Hydrogen
b) Chlorine
c) Oxygen
d) Nitrogen

Answer:

b) Chlorine

Explanation:

In the electrolysis of brine, chlorine is released at the anode.

12. Which process involves the use of bacteria to extract gold from gold-bearing minerals?

a) Bioleaching
b) Roasting
c) Calcination
d) Carbon reduction

Answer:

a) Bioleaching

Explanation:

Bioleaching involves the use of bacteria to extract gold from gold-bearing minerals.

13. Which of the following elements is refined by the Mond process?

a) Iron
b) Zinc
c) Nickel
d) Silver

Answer:

c) Nickel

Explanation:

Nickel is refined using the Mond process which involves the conversion of nickel to its volatile carbonyl complex.

14. The metal which can be extracted by the cyanide process is:

a) Aluminum
b) Copper
c) Silver
d) Zinc

Answer:

c) Silver

Explanation:

The cyanide process is used for the extraction of silver.

15. An amalgam is an alloy of:

a) Copper and zinc
b) Iron and carbon
c) Gold or silver with mercury
d) Aluminum and copper

Answer:

c) Gold or silver with mercury

Explanation:

An amalgam is an alloy of either gold or silver with mercury.

16. The chief ore of aluminum is:

a) Galena
b) Hematite
c) Bauxite
d) Magnesite

Answer:

c) Bauxite

Explanation:

Bauxite is the chief ore of aluminum.

17. The primary purpose of flux in metallurgical processes is to:

a) Enhance the reactivity of the ore
b) Convert impurities into slag
c) Increase the yield of metal
d) Remove moisture from the ore

Answer:

b) Convert impurities into slag

Explanation:

Flux helps in converting the impurities into slag which can be easily removed.

18. Which metal is extracted by the Hall-Heroult process?

a) Iron
b) Aluminum
c) Copper
d) Zinc

Answer:

b) Aluminum

Explanation:

Aluminum is extracted by the Hall-Heroult process from purified alumina.

19. Which of the following processes is not a chemical refining process?

a) Cupellation
b) Zone refining
c) Electrolytic refining
d) Vapor-phase refining

Answer:

b) Zone refining

Explanation:

Zone refining is a physical method used to purify metals based on the principle of the difference in solubility.

20. Calcination of an ore is done to:

a) Convert ore to oxide
b) Remove moisture and volatile impurities
c) Convert ore to chloride
d) Convert ore to sulphide

Answer:

b) Remove moisture and volatile impurities

Explanation:

Calcination is carried out to remove moisture and volatile impurities by heating the ore below its melting point.

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