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 metals and non metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which of the following methods is not used to coat metallic elements to prevent corrosion?

  1. Electroplating

  2. Metal cladding

  3. Metal spraying

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

Electroplating is the process of plating one metal onto another by hydrolysis, most commonly for decorative purposes or to prevent corrosion of a metal. Metal cladding is the bonding together of dissimilar metals. It is different from fusion welding or glueing as a method to fasten the metals together. In metal spraying a wide range of metals is sprayed onto the surface of another metal. All of these methods are used to prevent corrosion.

Multiple choice chemistry electrical conductivity of liquids effects of oxidation reactions in daily life corrosion of metals electroplating and its application
Assertion: Zinc is coated on the iron to prevent corrosion in a process called galvanization.
Reason: Zinc is a stronger reducing agent than iron and is more easily oxidized than iron.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Assertion is false but Reason is true

  5. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Coating of iron with zinc to prevent corrosion is called galvanization.
Steel is dipped in a bath of molten zinc. The zinc coated iron is called galvanized iron. Zinc $(E^o=-0.763 : V)$ is stringer reducing agent than iron $(E^o=-0.44 : V)$ and is more easily oxidized than iron . Thus during corrosion, Zn is oxidized instead of Fe.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Any article of iron if left in open for some time, acquires a film of brownish substance (rust) having chemical formula:

  1. $Fe _3O _4$
  2. $Fe _2O _3$

  3. FeO
  4. $Fe(OH) _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron reacts with air to form iron oxide(III) which is known by the name rust or rusting of iron. Rust is an iron oxide or red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Rust consist of hydrated iron oxide.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Corrosion occurs due to:
a) action of water on the metal.
b) action of air on the metal.
c) action of temperature on the metal.

  1. a, b

  2. b, c

  3. a, c

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

An action of air and water gradually eats up the metal. This eating up of metals by the action of air and moisture on their surface is called corrosion.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which of the following methods is suitable for preventing an iron frying pan from rusting?

  1. Applying grease

  2. Applying paint

  3. Applying a coating of zinc

  4. All of the above.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

We can prevent iron getting rusted by applying a coat of zinc or a thin coat of plastic helps to prevent rust. The process for coating metal like iron or steel with a thin zinc layer is known as galvanization.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application
The surface of some metals, such as iron, is corroded when they are exposed to moist air for a long period of time. This phenomenon is known as __________ .

  1. Erosion

  2. Corrosion

  3. Rusting

  4. Both A and B
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The process where metals are degraded by reaction with moisture and air is called corrosion. When specifically referring to iron, it is called rusting.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

According to electrochemical theory of corrosion involves:

  1. cathodic dissolution of metal

  2. cathodic deposition of metal

  3. anodic dissolution of metal

  4. anodic deposition of metal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In corrosion $Fe^{2+}$ get oxidised to $Fe^{3+}$ which takes place on anode surface.

Anode: $Fe(s)\rightarrow { Fe }^{ 2+ }+2{ e }^{ - }$
Cathod:${ O } _{ 2 }+4{ H }^{ + }+4{ e }^{ - }\rightarrow { 2H } _{ 2 }O$
Overall:$2Fe(s)+{ O } _{ 2 }+4{ H }^{ + }\rightarrow 2{ Fe }^{ 2+ }+{ H } _{ 2 }O$
             ${ 4Fe }^{ 2+ }+{ O } _{ 2 }+(2+4x){ H } _{ 2 }O\rightarrow { 2Fe } _{ 2 }{ O } _{ 3 }.x{ H } _{ 2 }O+4{ H }^{ + }$
So,$Fe^{3+}$ get deposited on metal surface.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which metal is usefull for protection of iron by corrosion?

  1. Aluminium

  2. Sodium

  3. Zinc

  4. Copper
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A thin layer of zinc coats other metals such as iron. It protects the iron from corrosion. Also since zinc is a more reactive metal it acts as a sacrificial metal. The oxygen in the air reacts with zinc to form zinc oxide, thus protecting the iron.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which of the following will be most easily corroded in moist air?

  1. $Zn$
  2. $Fe$
  3. $Ni$
  4. $Sn$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
When iron ( $Fe$ ) is exposed to moist air, it reacts with oxygen to form rust.

The formation of a rust is a very complex process, which is thought to begin with the oxidation of iron to ferrous ( iron"+2") ions.

Iron metal reacts in moist air by oxidation to give a hydrated iron oxide. This does not protect the iron surface to further reaction since it flakes off, exposing more iron metal to oxidation. This process is called rusting.
Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

State True or False.
Corrosion of motor cars is the major problem in the winter, when salt is spread on road to melt ice and snow.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If two metals are made to touch under the surface of an electrolyte they constitute a short circuited cell. Corrosion is a greater problem in winter when the salts are laided as chromium and iron are the two metals and NaCl act as an electrolyte.

Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

State True or False.

Corrosion of iron is a redox process.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rusting of iron is corrosion of iron. Rusting of iron takes place when iron corrodes in the presence of water and oxygen. It is a redox reaction whereby oxygen acts as an oxidising agent while iron acts as a reducing agent. When iron is contact with water, a simple chemical cell is formed.