Chemistry · Science General

Metallurgical Processes

1,403 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 changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which of the following statements is/are incorrect ?

  1. Rust is $Fe _{2}O _{3}$

  2. Zn - Cu cell is called Daniell cell.

  3. Saline water slows down rusting.

  4. Pure metals undergo corrosion faster than impure metals.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

Correct statements are given below:

a. Rust is $Fe _{2}O _{3}.xH _{2}O$.
b. Correct.
c. Saline water fastens the rusting.
d. Pure metals undergo corrosion slower than impure metals.

Hence, options A, C and D are correct options

Multiple choice chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

The presence of electrolytes ................ the rate of corrosion. 

  1. increases

  2. decreases

  3. sharply decreases

  4. does not effect
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The presence of electrolyte increase the concentration of electron and thus increasing the mobility of electron due to which rate of corrosion increases.

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

Aluminium is more reactive than iron. But aluminium is less easily corroded than iron because:

  1. aluminium is a noble metal

  2. oxygen forms a protective oxide layer on aluminium surface

  3. iron unergoes reaction easily with water

  4. iron forms both mono and divalent ions
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Corrosion resistance of aluminium is due to formation of thin layer of aluminium oxide that forms when metal is exposed to air and prevents further oxidation. It is called as protective passivation.

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

Which of the following statement is not true?

  1. metals produce a ringing sound when struck hard

  2. copper doesn't get rusted

  3. coal and sulphur are soft and dull in appearance

  4. magnesium and phosphorous burn vigorously in air
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Copper gets oxidized to form green oxide layer in the presence of air but this is not rusting, this layer is known as patina means tarnishing of copper into bluish green layer.

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

Lead pipes are readily corroded by:

  1. water

  2. acetic acid
  3. conc. $H _2SO _4$
  4. dil. $H _2SO _4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Corrosion of lead is strongly accelerated by traces of acetic acid. Acetic acid in the presence of oxygen rapidly attacks lead and produces very soluble lead(II) acetate which precludes the use of lead to process or store wine or fruit juice.

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

When a corroded metal object is rubbed by a sand paper then:

  1. outer metal surface is removed

  2. metal becomes thin

  3. outer corroded layer will be removed

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

The metals lose their shine and become dull when exposed to air for a long time. Due to the formation of oxides, when the surface is rubbed by a sand paper, then the outer corroded layer is removed.

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

According to the electrochemical concept, corrosion occurs at :

  1. anodic area of metal

  2. cathodic area of metal

  3. both cathodic and anodic areas of metal

  4. neither cathodic area nor anodic areas of metal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Corrosion can be defined as the deterioration of materials by chemical processes. 

Of these, the most important by far is electrochemical corrosion of metals in which the oxidation process $M \rightarrow M^+ + e^-$ is facilitated by the presence of a suitable electron acceptor. This is possible because metals are conductive and so, the electrons can flow through the metal from the anodic to the cathodic regions. 
Metallic corrosion occurs when metal atoms are oxidized and subsequently leave the metal lattice as ions. The oxidation reaction of the metal is referred to as the anodic half-reaction. The areas on a metal surface where oxidation occurs are referred to as anodes.

Option A is correct.

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

What is corrosion?

  1. When metal is gradually destroyed through chemical reactions

  2. When metal is created through chemical reactions

  3. When a redox reaction takes place

  4. When a metal is destroyed after exposure to a gas

  5. When a solid is destroyed through chemical reactions
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Corrosion occurs when a redox reaction takes place.

Corrosion is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide, hydroxide, or sulfide. It is the gradual destruction of materials by chemical and/or electrochemical reaction with their environment.
It also gradually destroys the element through chemical reactions

Hence, the correct options are $A$ and $C$

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

Which of the following metals has been used for building boats because it has resistance to corrosion by sea water?

  1. Copper

  2. Nickel

  3. Fungsten

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

Titanium is used for building boats.

Inert metals which do not react with gases in air seen as oxygen are found to be non-corrosive.
It is corrosion resistance because it forms stable, protective, oxide film when $Ti$ is exposed to oxide film.

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

In the rusting of iron, iron has been:

  1. oxidised

  2. reduced

  3. vaporised

  4. decomposed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In corrosion, metal is oxidised by loss of electrons to oxygen to form metal oxide. In rusting of iron, at one spot of the iron object oxidation occurs and that spot behaves as an anode.
Anode:    $Fe(s)  →  Fe^{2+}(aq) + 2e^-  $
Cathode: $4e^- + 4H^+(aq) + O _2(aq)  →  2H _2O(l)$
Multiple choice chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Iron nails rust fast when used for fixing plates or strips of aluminium on a building. Similarly, a water pipe made of iron corrodes faster when connected to a pipe of copper. This happens because of the?

  1. Greater wetting of iron

  2. Easier flow of electrons to iron

  3. Higher rusting power of iron

  4. Chemical reduction of iron
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is due to higher rusting power of iron.

When iron pipe is connected to copper corrosion is caused by self induced current created. The current is generated due to difference in electrical potential. The water act as a weak electrolyte.