Chemistry · Science General

Metallurgical Processes

1,436 Questions

This section explores key metallurgical processes including ore concentration, pyrometallurgy, and metal refining. It also covers corrosion and the properties of refractory materials. These chemistry questions are relevant for engineering and science entrance tests.

Pyrometallurgy furnacesMetal refining techniquesCorrosion protection methodsOre concentrationAuto reduction process

Metallurgical Processes Questions

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

Which of the following methods is used to remove lead present in silver ?

  1. Cupellation

  2. Distillation

  3. Poling

  4. Lavigation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cupellation is a process of separation of gold or silver from impurities by melting the impure metal in a cupel (a flat porous dish made of refractory or high-temperature resistant material  ) and then directing a blast of hot air on it in a special furnace. The impurities, including lead,copper, tin, and other unwanted metals, are oxidized and partly vaporized and partly absorbed into the pores of the cupel.

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

Poling process:

  1. reduces $SnO _2$ to Sn

  2. oxidizes impurities like iron and removes as scum

  3. uses green poles

  4. uses brown poles
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Poling: A refining process of crude metal for removing metal oxide impurities by stirring molten metal in a ladle with a pole of green wood (poles).


In the poling process, the reduction of oxides to metal atom will be done.

Ex: Extraction of copper from copper oxide and Sn from $SnO _2$.

Hence options A,B & C are correct.

Multiple choice chemistry chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

The process of depositing thin layer of a metal over an another metal with a help of electric current is called :

  1. electrorefining

  2. electroplating

  3. thermoplating

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electroplating is the process of plating one metal onto another, for decorative purposes or to prevent corrosion of a metal. 

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

The process of electrolysis is used in:

  1. extraction of metals

  2. electroplating

  3. refining of metals

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Answer is D.
Electrolysis has wide applications in industries. Some of the important applications are, as follows, 
(i) Production of hydrogen by electrolysis of water. 
(ii) Manufacture of heavy water. 
(iii) The metals like K, Mg, Al, etc., are obtained by electrolysis of fused electrolytes. 
(iv) Non-metals like hydrogen, fluorine, chlorine are obtained by electrolysis. 
(v) In this method pure metal is deposited at cathode from a solution containing the metal ions, etc. 
(vi) Compounds like NaOH, KOH, white lead, etc. are synthesised by electrosynthesis method.
(vii) Electroplating: The process of coating an inferior metal with a superior metal by electrolysis is known as electroplating. 
Hence, the options A, B and C are correct.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

The most durable metal plating on iron to protect against corrosion is:

  1. tin plating

  2. zinc plating

  3. copper plating

  4. nickel plating
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Metal plating protects the iron against corrosion by forming a sacrificial layer. This metal layer itself gets oxidize instead of iron and thus protects the iron itself. 


For a metal to be used as plating, its oxidation should be preferred over iron and thus should have lower reduction potential than iron. 

Among the given options, zinc has a lower reduction potential than iron and thus can be used for plating. The process is called galvanization.

Hence, option B is correct. 

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

In the electrolysis of molten $Al _2O _3$ with inert electrodes:

  1. Al is oxidized at anode to $Al^{3+}$
  2. $O _2$ gas is produced at anode
  3. $O^{2-}$ is reduced at cathode
  4. $O$ is oxidized at anode
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The electrodes are inert so that they do not involve the electrode reactions but transfer electrons through them. Since the silvery metal i.e. $Al$ is produced at cathode.

At cathode: $Al^{3+}+3e^- \longrightarrow Al$
At anode, $O _2$ bubbles off.
At anode; $2O^{2-}\longrightarrow O _2+4e^-$
The cell reaction: $2Al _2O _3\longrightarrow 4Al+3O _2$

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

By selecting electrolyte as sodium argentocyanide for electroplating of the metal article with silver. Which of the following condition ensures that deposit is smooth, firm and long-lasting?

  1. low direct current should be passing for long time

  2. low indirect current should be passing for long time

  3. low direct current should be passing for short time

  4. low indirect current should be passing for long time.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For high-quality electroplating, a low current density is required to ensure a smooth, uniform, and firm deposit. A high current would result in a rough, powdery, or non-adherent deposit.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

In the electroplating of silver, $AgNO _3$ solution is usually used as:

  1. oxidant

  2. reductant

  3. electrode

  4. electrolyte
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The process of depositing a thin layer of silver electrolytically on the metal surface is called silver plating. The article to be silver-plated is used as cathode while anode consists of pure silver. 


The bath contains a solution of potassium argentocyanide ($AgNO _3$ + excess of KCN). The complex ion is very stable and ionisation is very small at a time with the result slow and uniform deposition of silver takes place. 

$[Ag(CN) _2]^2 \rightleftharpoons Ag^+ + 2CN^-$


Hence, option D is correct.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

Galvanization of iron denotes coating with:

  1. copper

  2. aluminium

  3. silver

  4. none of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Galvanization is the process of applying a protective zinc coating to steel or iron, to prevent rusting. Galvanization of Iron meaning coating with zinc.


It forms a coating of corrosion-resistant zinc which prevents corrosive substances from reaching the more delicate part of the metal. The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed iron will still be protected by the remaining zinc.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

Which of the following is not an electrochemical process?

  1. Transmission of nerve impulses in human body

  2. Rusting of iron

  3. Lightning

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both transmission of nerve impulse and  rusting of iron are results of electrochemical reactions.In transmission of nerve impulse numerous small molecules function as neurotransmitters at various chemical synapses.Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Lightning is a sudden electrostatic discharge during an electrical storm between electrically charged regions of a cloud.