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 ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

The process in which metal surface is made inactive is called:

  1. passivation

  2. galvanizing

  3. corrosion

  4. pickling
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build from spontaneous oxidation in the air.

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

Corrosion is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide. 

Pickling is the process of preserving or expanding the lifespan of food by either anaerobic fermentation in brine or immersion in vinegar. 
Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Some properties of aluminium are listed.
1 It has mechanical strength.
2 It is resistant to corrosion.
3 It has a low density.
4 It conducts heat.
Which three properties make aluminium useful for making the bodies of aircraft?

  1. $1, 2$ and $3$
  2. $1, 2$ and $4$
  3. $1, 3$ and $4$
  4. $2, 3$ and $4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Solution:- (A) $1, \; 2$ and $3$

Aluminium is useful in making of aircraft bodies due to its mechanical strength, low density and corrosion resistance.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Which of the following methods can be used for the preparation of anhydrous aluminium chloride?

  1. Heating ${Al Cl _3.6 H _2 O}$

  2. Heating a mixture of alumina and coke in a current of dry chlorine

  3. Passing dry HCl gas over heated aluminium powder

  4. Passing dry chlorine over heated aluminium
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation

Anhydrous aluminium chloride can be prepared by the following methods:
(B) Heating a mixture of alumina and coke in a current of dry chlorine.
$Al _2O _3+3C+3Cl _2 \rightarrow 2AlCl _3+3CO\uparrow$


(C) Passing dry HCl gas over heated aluminium powder.
$2Al+6HCl \rightarrow 2AlCl _3+3H _2$

(D) Passing dry chlorine over heated aluminium.
$2Al+3Cl _2 \rightarrow 2AlCl _3$

It can not be obtained by heating of $AlCl _3.6H _2O$, because $AlCl _3$ is covalent and hence when the water of crystallisation is evaporated, $AlCl _3$ will react with the water to form the hydroxide.

Multiple choice geography rivers, coasts and glaciation rivers rivers and their work exogenic forces

What is rust?

  1. Chemical reaction between oxygen and iron

  2. Chemical reaction between carbon dioxide and iron

  3. Chemical reaction between alkalis and iron

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

The iron in the rock comes in contact with water and chemical reaction takes place between iron and oxygen. Hence,a reddish coloured layer forms on the rocks. This is called rust.

Multiple choice chemistry environmental chemistry biochemistry and the environment green chemistry strategies to control environmental pollution and green chemistry

Faraday has developed a plating process to make high-performance chrome coatings from trivalent chromium instead of highly toxic hexavalent chromium. This is an application of:

  1. Green revolution

  2. Green chemistry

  3. waste management

  4. revolution resource recovery
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Faraday has developed a plating process to make high-performance chrome coatings from trivalent chromium instead of highly toxic hexavalent chromium. It involves the production of alternate product which is more friendly to environment. Hence, this is an application of Green chemistry.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

Why crystallisation is used as a method of obtaining pure $CuSO _4$ from impure sample?

  1. Because $CuSO _4$ is a liquid
  2. Because $CuSO _4$ is a solid
  3. Because $CuSO _4$ is a gas

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

Crystallisation is a method used to purify solids. $CuSO _4$ is solid, hence it can be obtained as in a pure cystal form from impure samples using cystallisation.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

The copper sulphate solution is heated gently on a water bath for :

  1. proper mixing of the sample

  2. evaporation of water

  3. dissolving the copper sulphate in solution

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

Pure copper sulphate is obtained from an impure sample by re-crystallization. The sample is mixed in water and filtered to remove impurities. It is then heated gently on a water bath for evaporation of water. Thus, a saturated solution is obtained.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

To crystallize copper sulphate, it is dissolved in water and a small quantity of ................. is also added.

  1. concentrated nitric acid

  2. dilute hydrochloric acid

  3. dilute sulphuric acid

  4. dilute nitric acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To crystallise copper sulphate, water is dissolved and a small quantity of dilute sulphuric acid is added to prevent the hydrolysis of copper sulphte. The impurities left behind in the solution are removed by filtration.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

When are the crystals of copper sulphate obtained?

  1. when hot acidic copper sulphate solution is cooled gradually.

  2. when cold acidic copper sulphate solution is heated gradually.

  3. when hot acidic copper sulphate solution is cooled suddenly.

  4. when cold acidic copper sulphate solution is heated suddenly
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When hot acidic $ copper : sulphate$ solution is cooled gradually, the crystals of  $ copper : sulphate$ are obtained.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

Why crystallisation is used for obtaining pure copper sulphate from an impure sample rather than simple evaporation?

  1. Some impurities may remain dissolved in the solution even after filtration. On evaporation, these may contaminate the solid

  2. Because crystallisation is comparatively easier than evaporation

  3. Because crystallisation is comparatively faster

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

Crystallisation technique is better than simple evaporation technique as some solids decompose and some impurities may remain dissolved in the solution even after filtration. On evaporation, these contaminate the solid.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

After purification by crystallization, copper sulphate crystals can be obtained by :

  1. filtration

  2. passing through funnel

  3. evaporation to dryness

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

Impure copper sulphate is dissolved in water and heated till saturation. It is then cooled and crystals of pure copper sulphate are formed. These crystals are then separated by filtration and then dried.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

What are the characteristics of the solvent used during purification of copper sulphate by crystallization?

  1. Not dissolve the substance at room temperature

  2. Dissolve the impurities at room temperature

  3. Does not dissolve the impurities at high temperature

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

Choosing an appropriate solvent is the important process of crystallisation, as crystallisation works only when a proper solvent is used. It is important to choose a solvent that will not dissolve the substance at room temperature. But as the temperature of the solvent increases, the solubility of the solute also increases. At the same time, the impurities that are present must either be soluble in the solvent at room temperature or must be insoluble in the solvent at a high temperature. If the solvent is not hot when the dissolution is carried out, too much solvent will be used, leading to diminished yield.

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

During concentration (saturation), copper sulfate solution is constantly stirred to :

  1. ensure uniform evaporation

  2. prevent formation of a solid crust

  3. both a and b

  4. it is not stirred during saturation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To concentrate the filtrate of impure copper sulphate, the china dish containing filtrate is heated gently with constant stirring. This is done to ensure uniform evaporation and to prevent formation of a solid crust. 

Multiple choice chemistry separation of matter crystals and crystallisation filtration and crystallisation other methods of separation

Why is dilute sulphuric acid added during crystallization of copper sulphate?

  1. Prevent hydrolysis of copper sulphate

  2. Prevent crystallization of copper sulphate

  3. Enhance formation of large crystals

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

To crystallise copper sulphate, it is dissolved in water and a small quantity of dilute sulphuric acid is added to prevent the hydrolysis of copper sulphte. The impurities left behind in the solution are removed by filtration.