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 chemical effects of electric current applications of electrolysis electroplating extraction of metals by electrolysis

Chromium plating is done to make the object scratch proof and appear shiny.

  1. True

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

Chromium plating is a technique of electroplating in which a thin layer of chromium is coated onto a metal object. The layer is decorative (shiny), provide corrosion resistance, ease cleaning procedures, and increase surface hardness (scratch resistance).


Hence, option A is correct.

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

To protect iron from corrosion and rusting , it is electroplated with 

  1. Zinc

  2. Chromium

  3. Nickel

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

Iron is coated with a more active metal like Zinc. This is a sacrificial method. If the rusting conditions are met, zinc rusts before iron and prevents iron from rusting. Zinc makes a protective layer with Zn(OH)2 and ZnCO3

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

The process of depositing a thin layer of desired metal over another metal by passing an electric current through some electrolyte is called :

  1. electric shielding

  2. electric polishing

  3. electric coating

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

Electroplating is the application of electrolytic cells in which a thin layer of metal is deposited onto an electrically conductive surface.


Hence, option D is correct.

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

Electroplating does not help

  1. fine finish to the surface

  2. shining appearance

  3. metals to become hard

  4. protect metals against corrosion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electroplating is primarily used to change the surface properties of an object like appearance, corrosion protection, lubricity etc.  Thus, electroplating does not help in making the metals become hard. 

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

Chromiumhas a shiny appearance and lt does not corrode

  1. True

  2. False

  3. Ambiguous

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

Answer is A.
Electroplating is a very useful process. It is widely used in industry for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which the metal of the object lacks. For example, chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, bicycle handlebars, wheel rims and many others.
Chromium has a shiny appearance. It does not corrode. It resists scratches. However, chromium is expensive and it may not be economical to make the whole object out of chromium. So the object is made from a cheaper metal and only a coating of chromium over it is deposited.
Hence, electroplating of chromium is done on objects like water taps and cycle bell to give them a shiny appearance and prevent them from corrosion. The statement is true.

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

In electroplating of the silver spoon with gold, the silver spoon is cleaned with a dilute acid solution to remove the  _________  from its surface.

  1. oxide layer

  2. chloride layer

  3. silver layer

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

The silver spoon is cleaned with a dilute acid solution to remove the oxide layer from its surface and washed in running water until it is free from the acid.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Which of the following is/are always true electroplating ?

  1. Copper is used as cathode

  2. Cathode always gins weight while anode always loses weight

  3. Iron is coated with nickel or chromium to prevent from rusting.

  4. Ammeter reading during. electroplating steadily decreases.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In electroplating, the object to be plated is the cathode. While the cathode gains weight, the anode only loses weight if it is made of the metal being plated (sacrificial anode). Option A is the most general correct statement regarding the setup.

Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following defect is seen in $FeO$? 

  1. Metal excess defect

  2. Metal deficiency defect

  3. Displacement defect

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

$FeO$ has metal deficiency defect. Metal deficiency defect is supposed to arise when there are lesser number of positive ions than negative ions. In case of $FeO$, the positive ions are missing from their lattice sites. 

The additional negative charge is balanced by some nearby metal ion by acquiring one more positive charge. It happens in $FeO$ because $Fe$ has capacity of showing variable oxidation states.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

What is the process of leaching in case of low grade copper ores?

  1. Leaching is carried out with $NaOH$ and $O _2$
  2. Leaching is carried out with $NaCN$
  3. Leaching is carried out with acids in presence of $O _2$

  4. Leaching is carried out by boiling the ore with water
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Leaching of low grade copper ores is carried out with acid or bacteria, when copper goes into solution as $Cu^{2+} _{(aq) }+ H _{2(g)}\rightarrow Cu _{(s)}+2H^+ _{(aq)}$ 

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

How do we separate two sulphide ores by froth floatation method?

  1. By using excess of pine oil.

  2. By adjusting proportion of oil to water or using depressant.

  3. By using collectors and froth stabilities like xanthates.

  4. By using some solvent in which one of the sulphides is soluble.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

By using depressants or adjusting proportion of oil to water, selective prevention of one sulphide ore from coming to the froth is possible.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

An ore of tin containing, $FeCrO _4$ is concentrated by:

  1. gravity separation

  2. magnetic separation

  3. forth floatation

  4. leaching
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Magnetic separation based on differences in magnetic properties of the ore components.
  •  If either the ore or the gangue is attracted towards the magnetic field, then the separation is carried out by this method. 
  • For example, iron ores are attracted towards the magnet, hence, non–magnetic impurities can be separated from them using magnetic separation.
  • Here,$FeCrO _4$ being an iron ore can be separated by magnetic separation.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Removal of the unwanted materials like sand, clays, etc. from the ore is known as __, ___ or _____.

  1. concentration, dressing, benefaction

  2. separation, refining, gangue

  3. magnetic separation, Purification, gangue

  4. washing, refining, amalgamation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Removal of the unwanted materials (e.g., sand, clays, etc.) from the ore is known as concentration, dressing or benefaction.

  • Before proceeding for concentration, ores are graded and crushed to a reasonable size. 

  • The concentration of ores involves several steps and the selection of these steps depends upon the differences in physical properties of the compound of the metal present and that of the gangue.
Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

The significance of leaching in the extraction of aluminium is:

  1. it helps to remove the impurities like $SiO _2, Fe _2O _3,$ etc from the bauxite ore

  2. it converts the ore into oxide

  3. it reduces melting point of the ore

  4. it eliminates water from bauxite.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Bauxite is the principal ore of aluminium.  The impurities present in bauxite are $SiO _2$, iron oxides and titanium oxide ($TiO _2$). 
  •  $Al _2O _3$ is extracted out as sodium aluminate. The impurity, $SiO _2$ too dissolves forming sodium silicate. Other impurities are left behind.
$Al _2O _3+2NaOH+3H _2O \rightarrow 2Na[Al(OH) _4]$
  • Thus, leaching is used to remove the impurities present and hence option $A$ is the correct option.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Sulphide ore of zinc/copper is concentrated by:

  1. forth floatation

  2. electromagnetic process

  3. gravity process

  4. distillation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Froth floatation method is used for removing gangue from sulphide ores. In this process, a suspension of the powdered ore is made with water.
  • Collectors and froth stabilizers are added to it. Collectors (e.g., pine oils, fatty acids, xanthates, etc.) enhance non-wettability of the mineral particles and froth stabilizers (e.g., cresols, aniline) stabilize the froth.
  • The mineral particles become wet by oils while the gangue particles by
water.
  • A rotating paddle agitates the mixture and draws air in it. As a result, the froth is formed which carries the mineral particles. The froth is light and is skimmed off. It is then dried for recovery of the ore particles.