Tag: general principles and processes of isolation of elements

Questions Related to general principles and processes of isolation of elements

By annealing, steel :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. becomes soft

  2. becomes liquid

  3. become hard and brittle

  4. is covered with a thin film of $Fe _3O _4$

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Correct Option: A
Explanation:

By annealing, steel becomes soft.


In anealing, steel is first heated to bright redness and then cooled slowly.

When $FeCr _2O _4$ is heated with carbon an alloy called ferrochrome is obtained.

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. True

  2. False

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Correct Option: A
Explanation:

Ferrochrome is produced by reduction of  $Cr-ore$ (an oxide of Chromium and iron) with coal and coke.

Ferrochrome is iron-chromium alloy. So, the statement "when $FeCr _2O _4$ is heated with carbon an alloy Ferrochrome is obtained" is correct.

In iron metallurgy, lime stone is used :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. To obtain heat energy

  2. To reduce iron oxide into iron

  3. As an iron ore

  4. To remove sand ($SiO _2$)

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Correct Option: D
Explanation:

In the extraction of iron, the roasted ore is mixed with coke and lime stone (flux) and is then heated in the presence of air at high temperature in a furnace. Impurity of $SiO _2 $ is removed as calcium silicate $(CaSiO _3 slag)$.
$ CaCO _3\rightarrow CaO+CO _2$
$CaO+SiO _2\rightarrow CaSiO _3$

During smelting, an additional substance is added which combines with impurities to form a fusible product. It is known as :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Slag

  2. Mud

  3. Gangue

  4. Flux

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Correct Option: D
Explanation:

Flux is a substance which may be either acidic oxide $(Si{O} _{2})$ or basic oxide $(CaO, MgO)$. It combines with certain impurities (gangue particles) in order to form a substance called slag. This can be easily removed.

The pyrometallurgical operations involve the use of:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. High temperature

  2. Sulphide ores

  3. Electrolysis

  4. Complexation

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Correct Option: A
Explanation:

Pyrometallurgy employs high temperatures to carry out smelting and refining operations to extract metals from their minerals. 


Hydrometallurgy uses aqueous solutions to separate the desired metals. Finally, electrometallurgy employs electrical energy to extract and refine metals.

Hydro-metallurgical process of extraction of metals is based on :

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Complex formation

  2. Hydrolysis

  3. Dehydration

  4. Dehydrogenation

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Correct Option: A
Explanation:

Hydrometallurgy is a technique involving the use of aqueous chemistry for the recovery of metals from ores, concentrates, and recycled or residual materials. This process is used in extraction of less electro positive or less reactive metals like gold and silver by complex formation. 

For the pyrometallurgical method used for the extraction of copper from sulphide ore, which statement(s) is/are correct?

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Pyrometallurgy is a dry method

  2. It involves concentration by leaching the sulphide ore with dil. $H _2SO _4$

  3. It involves concentration of the sulphide ore by froth flotation process

  4. It involves concentration by leaching for every ore

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Correct Option: A,C
Explanation:
The copper is extracted from sulphide ore by pyrometallurgy which involves reduction of the concentrated ore at high temperature.
This process is a dry process.
In this process, the sulphide ore is concentrated by froth floatation process.
In this process, the sulphide ore is not concentrated by leaching with dil sulphuric acid.
Thus, statements B  and D are incorrect and statement A and C are correct.

Smelting involves reduction of metal oxide with:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Carbon

  2. Self reduction

  3. Magnesium

  4. Aluminium

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Correct Option: A
Explanation:

Smelting is used to produce a base metal from its ore. The reducing agent is commonly a source of carbon such as coke, or in earlier times charcoal.

Copper can he extracted by hydrometallurgy but not zinc because:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. Copper is comparatively less active metal as its reduction potential is high. It can be displaced from solutions of $Cu^{2+}$ ion by more active metals.

  2. Zn displaced from solution of $Zn^{2+}$ ion, a more reactive metal than it, but then readily react with water forming their corresponding ions and evolve hydrogen gas.

  3. Both (A) and (B) are correct.

  4. Copper can never be extracted by hydrometallurgy.

Show answer
Correct Option: C
Explanation:

Hydrometallurgy involves formation of aqueous complex compounds and is used in extraction of less electro positive or less reactive metals like gold and silver. 


  • Copper is  also comparatively less active metal as its reduction potential is high and it can be displaced from solutions of $Cu^{2+}$ ion by more active metals.

  • $Zn$ can also be displaced from solution of $Zn^{2+}$ ion by a more reactive metal than it, but then readily react with water forming their corresponding zinc ions and evolve hydrogen gas.

Metals which can be extracted by smelting process is/are:

thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

  1. $Sn$

  2. $Cu$

  3. $Zn$

  4. $Al$

Show answer
Correct Option: A,B,C,D
Explanation:

The process of extracting a metal from its oxide is known as 'smelting'. Most smelting processes involve direct reduction of the ore by carbon to metal and carbon dioxide. The production of primary aluminium is a good example of such a process.
Metals include copper, nickel, lead, zinc, silver, cobalt, gold, cadmium, etc.
Hence options A,B,C & D are correct.