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 physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

If a bimetallic strip is heated, it will

  1. Bend towards the metal with lower thermal expansion coefficient.

  2. Bend towards the metal with higher thermal expansion coefficient.

  3. Twist itself into helix.

  4. Have no bending.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A

A bimetallic strip consists of two metal strips fastened together. Metals are chosen that expand at different rates when the strips get hot. When one strip gets longer than the other, the combination has to bend. These strips are often used in thermostats in houses to control the house temperature. When the strip is cold, it bends one way, and as it gets hotter it bends the other way.

Multiple choice physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

Iron or steel is used in reinforcement in concrete because

  1. Concrete has high coefficient of expansion than iron or steel

  2. Concrete has low coefficient of expansion than iron or steel

  3. Both have nearly equal coefficient of expansions

  4. Iron or steel is a good conductor of heat
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The properties of thermal expansion for both steel and concrete are approximately the same as both have nearly equal coefficient of expansion . This along with excellent bendability property makes steel the best material as reinforcement in concrete structures.

Multiple choice aluminium patterns and properties of metals chemistry

Cryolite is:

  1. ${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina for decreasing electrical conductivity
  2. ${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina for lowering the melting point of alumina
  3. ${Na} _{3}Al{F} _{6}$ and is used in the electrolytic purification of alumina
  4. ${Na} _{3}Al{F} _{6}$ and is used in the electrolysis of alumina
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation
  • Molten cryolite $(Na _3AlF _6)$ is used as a solvent for aluminium oxide $(Al _2O _3)$ in the Hall–Héroult process, used in the refining of aluminium. 
  • It decreases the melting point of molten (liquid state) aluminium oxide to 900-1000 °C from 2000-2500 °C. Thus cryolite makes the extraction of aluminium profitable. 
  • Hence both option B and D are correct .
Multiple choice aluminium patterns and properties of metals chemistry

In the purification of $Al$ by Hoop's process the correct statement is 

  1. electrolytic cell is iron and it contains three layer mass
  2. upper layer is pure $Al$ and Carbon rods in it are cathode and the bottom layer contains impure $Al$ and carbon lining of the cell is anode

  3. Electrolyte is the middle layer with fused mixture of flouride.

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

Hoop's process for aluminum purification uses a three-layer electrolytic cell. The bottom layer is impure aluminum (anode), the middle is a fused fluoride electrolyte, and the top is pure aluminum (cathode).

Multiple choice aluminium patterns and properties of metals chemistry

In thermite welding, aluminium acts as a/an:

  1. solder

  2. flux

  3. oxidising agent

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

In thermite welding, aluminium acts as reducing agent. Aluminium is used in thermite welding of broken iron parts. The reduction of ferric oxide by aluminium is highly exothermic and therefore, the iron formed will be in the molten state. Thermite reaction involving aluminium is also called Goldschmidt alumino thermic reaction.

Multiple choice aluminium patterns and properties of metals chemistry

$Al$ is more reactive than iron but it is less easily corroded than iron because :

  1. it is a noble metal

  2. oxygen forms a protective oxide layer

  3. iron undergoes easily reaction with water

  4. iron formsmono and divalent ion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Aluminum unlike iron ,does not corrode in moist conditions. Its surface is protected by layer of aluminium oxide. This prevents thealluminium to come in contact with air and oxygen. The layer of aluminium oxide do not vanish, unlike rust which can flake off the surface of iron and steel objects. So $Al$ is covered with a layer by the oxygen

Hence option B is correct.

Multiple choice aluminium patterns and properties of metals chemistry

Aluminium metal gets corroded or 'rusted' in places that are near to the sea, because the oxide film that protects it:

  1. is attacked by salt from sea water

  2. reacts with water

  3. is removed by sea water

  4. reacts with sand particles
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The presence of salt (or any electrolyte) in the water accelerates the reaction because it increases the conductivity of water, effectively increasing the concentration of ions in the water and so increasing the rate of oxidation (corrosion) of the metal.
Thusm aluminium metal is corroded in places that are near to the sea.
Multiple choice aluminium patterns and properties of metals chemistry

Serving trays for tea or food, made of aluminium, often have coloured finish. These finishes are formed when an electric current in passes, which creates an oxide of aluminium layer than absorbs dyes. This is called:

  1. Galvanizing

  2. Anodizing

  3. Sherardizing

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

Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized.

Hence option B is correct answer.

Multiple choice aluminium patterns and properties of metals chemistry

Metals rust when they come in contact with oxygen of the air that forms oxides and thereby destroys the metal. Which metal forms an oxide with oxygen, that protects it from further rusting:

  1. aluminium

  2. zinc

  3. iron

  4. copper
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Aluminium does not rust (corrode) because its surface is protected by a natural layer of aluminium oxide $\left( {Al} _{2}{O} _{3} \right)$. This prevents the metal below from coming into contact with air.
Multiple choice aluminium patterns and properties of metals chemistry

Aluminium, deposited as vapour on a glass, forms good mirrors, essentially because:

  1. the coating is much smoother

  2. it does not scratch

  3. it has better shine than silver

  4. it does not tarnish in air
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aluminium, deposited as vapour on a glass, forms good mirrors because it does not tarnish in air. If it tarnishes then the mirror would not be that good. Hence due to the property of it not tarnishing in air the mirror formed are good mirrors.

Multiple choice aluminium patterns and properties of metals chemistry

Crystalline metal can be transformed into metallic glass by :

  1. alloying

  2. pressing into thin plates

  3. slow cooling of molten metal

  4. very rapid cooling of molten metal
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Crystalline metal can be transformed into a metallic glass by very rapid colling of molten metal. On rapid cooling of molten metal gives amorphous solid which is nothing but metallic glass.
Hence option $D$ is correct.

Multiple choice chemistry materials around us and different types of houses materials around us matter and its states different states of matter

A table made by iron is solid because:

  1. it has fixed shape because of strong molecular forces.

  2. it can not be deformed easily because of strong molecular forces.

  3. it is metal.

  4. None of these.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The iron table is solid because the intermolecular force of attraction of the iron table is very strong, thus it is rigid and hence cannot be deformed.

Multiple choice salts salts and their classification acids, bases and salts chemistry

Which of the following methods is generally used for preparing $Zn(NO _3) _2$ salt?


1 : Neutralisation - insoluble base & dilute acid  
2 : Neutralisation - alkali & dilute acid      

3 : Simple displacement - active metal & dilute acid  
4 : Direct combination                     

5 : Precipitation [double decomposition]

  1. 2

  2. 3

  3. 4

  4. 5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Zinc metal with dilute nitric acid gives zinc nitrate.

So, simple displacement-active metal & dilute acid is the correct option for this.

$Zn+2HNO _3 \rightarrow Zn(NO _3) _2+H _2$

Hence, the correct option is $(B)$.

Multiple choice salts salts and their classification acids, bases and salts chemistry
State which of the following methods is generally used for preparing the $FeS$ salts
1: Neutralisation-insoluble base & dilute acid.
2: Neutralisation-alkali & dilute acid.
3: Simple displacement-active metal & dilute acid.
4: Direct combination.
5: Precipitation [double decomposition].

  1. 1

  2. 2

  3. 3

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


Iron(II) sulfide is obtained by heating of iron and sulfur which is a direct combination.
$Fe+S \longrightarrow FeS$


Hence, the correct option is $(D)$