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 production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

Cryolite and fluorspar are mixed with $Al _2O _3$ during electrolysis for extraction of aluminium to:

  1. increase the mass of the reaction mixture

  2. get other products at anode like fluorine

  3. lower the melting point and increase the conductivity of the electrolyte

  4. reduce aluminium oxide by cryolite
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the metallurgy of Aluminium, purified $Al _2O _3$ is mixed with $Na _3AlF _6$ or $CaF _2$ which lowers the melting point of mix and brings conductivity.

Multiple choice chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

In the metallurgy of aluminium:

  1. $Al^{3+} $ is oxdised to $Al _{(s)}$

  2. graphite anode is oxidised to carbon monoxide and carbon dioxide

  3. oxidation state of oxygen changes in the reaction at anode

  4. oxidation state of oxygen changes in the overall reaction involved in the process
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The oxidation state of $'O'$ does not change i neither the reaction occurring at the anode or the overall reaction as shown below.
At anode:-$C+{ O }^{ 2- }\longrightarrow CO+2{ e }^{ - };C+2{ O }^{ 2- }\longrightarrow C{ O } _{ 2 }+4{ e }^{ - }$
The released electrons used at cathode and here Graphite  is oxidized to $'CO'$ and $C{ O } _{ 2 }$
Multiple choice chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

In the extraction of aluminium,
Process X: applied for red bauxite to remove iron oxide (chief impurity)
Process Y: applied for white bauxite to remove Z (chief impurity). 

Then, Process X and impurity Z are:

  1. X $=$ Hall - Heroults process & Y$=$ $SiO _{2}$
  2. X $=$ Bayers process and Z $=$ $SiO _{2}$
  3. X $=$ Serpecks process and Y $=$ iron oxide
  4. X $=$ Baeyers process and Y $=$ iron oxide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bayer's process is used for beneficiation of red bauxite.
Serpeck's process is used for beneficiation of white bauxite. 
Reaction to remove impurity from white bauxite is:
$SiO _2+2C\rightarrow Si+2CO$ .

Multiple choice chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

In electrtolysis of $Al _2O _3$ by Hall-Heroult process:

  1. Cryolite $Na _3[AIF _6]$ lowers the melting point of $Al _2O _3$ and increases its electrical conductivity.
  2. $Al$ is obtained at cathode and probably $CO _2$ at anode

  3. both (a) and (b) are correct

  4. none of the above is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The electrolysis of alumina by Hall and Heroult's process is carried by using a fused mixture of alumina and cryolite  along with minor quantities of aluminum fluoride and fluorspar. The addition of cryolite and fluorspar increases the electrical conductivity of alumina and  lowers the fusion temperature. Thus, the option A is correct. Also at anode, alumina reacts with fluorine to give oxygen. The liberated oxygen reacts with carbon to form $CO$ and $CO _2$. These gases are liberated at anode.

Multiple choice chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

Which one of the following statements is incorrect?

  1. In the aluminothermite process, aluminium acts as reducing agent.

  2. Lead is extracted from its chief ore by both carbon reduction and self-reduction.

  3. Zinc is extracted from its chief ore by carbon reduction.

  4. Extraction of gold involves the leaching of ore with cyanide solution followed by reduction with zinc.

  5. In Hall-Heroult process, the electrolyte used is a molten mixture of alumina, sodium hydroxide and cryolite.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation
(1) $Cr _{2}O _{3}+2Al\rightarrow Al _2O _3+2Cr^{3+}$
(2) $2PbS+2PbO\rightarrow 2PbO+2SO _{2}$
$PbS+2PbO\rightarrow 3Pb+SO _{2}$ (self reduction)
$PbO+C\rightarrow Pb+CO$ (carbon reduction)
(3) $ZnO+C\rightarrow Zn+CO$ (carbon reduction)
(4) $4Au(S)+8CN(aq)+2H _{2}O(aq)+O _{2}(g)\rightarrow 4[Au(CN) _{2}]^{-}(aq)+4OH^{-}(aq)$ - leaching
$2[Au(CN] _{2}]^{-}(aq)+Zn(S)\rightarrow 2Au(S)+[Zn(CN) _{4}]^{2-}(aq)$ - reduction
(5) It is molten mixture of alumina and cryolite
Multiple choice chemistry industrial inorganic chemistry extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

The following question is relevant to the extraction of Aluminium:
Along with cryolite and alumina, another substance is added to the electrolyte mixture. the substance is ___________.

  1. Fluorspar

  2. Mica

  3. NaCl

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

Fluorspar is the substance act as a solvent and it increases conductivity. (Pure alumina melts at about $2000^oC$ and is a bad conductor of electricity. If fused cryolite and fluorspar is added, the mixture melts at $900^oC$ and  $Al _2O _3$ becomes a good conductor of electricity.)

Multiple choice chemistry industrial inorganic chemistry extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

A compound added to lower the fusion temperature of the electrolytic bath in the extraction of Al is ___________.

  1. cryolite and fluorspar

  2. Bauxite

  3. Iron and fluorspar

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

Pure alumina melts at about $2000^oC$ and is a bad conductor of electricity. If fused cryolite and fluorspar is added, the mixture melts at $900^0C$ and $Al _2O _3$ becomes a good conductor of electricity.

Multiple choice business organisation and correspondence life is precious road safety and pollution pollution of natural resources air pollution and its effects

For corrosion of metals, there should be

  1. Exposed surface of metal

  2. Moisture

  3. Air

  4. All the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Corrosion is a natural process of formation of oxides of metal on reaction with oxygen and moisture present in the air. Generally, all metals can corrode. A layer of rust forms on the surface of metals such as in case of iron which corrodes very fast on exposure to air. Hence, for corrosion of metals, the surface of metal should be exposed to air and there should be moisture in the air.
Hence, all the given options are correct.
So, the correct answer is 'All the above'.
Multiple choice geography crafts and industries development of industries in india traditional crafts and decline of indian industries impact of british rule on kerala

The method of obtaining Wootz by heating black magnetite ore in the presence of carbon in a sealed clay crucible inside a charcoal furnace is called ______.

  1. Tamilakam method

  2. Srilankan method

  3. Magadhan method

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

The specific process of producing high-quality Wootz steel in South India using crucibles and charcoal furnaces is historically associated with the Tamilakam region.

Multiple choice chemistry endothermic and exothermic reactions endothermic reactions what are enthalpy changes energy change in chemical reactions

Decomposition of ferrous sulphate is a/an:

  1. precipitation reactions

  2. exothermic reactions

  3. endothermic reactions

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

Decomposition of ferrous sulphate is an endothermic reaction as it involves absorption of heat to form ferric oxide ($Fe _{2}O _{3}$), sulphur dioxide ($SO _{2}$) and sulphur trioxide ($SO _{3}$). The equation for this reaction can be written as:
$ 2FeSO _{4}(s)  \overset{heat}{\rightarrow}  Fe _{2}O _{3}(s)  +  SO _{2}(g)  +  SO _{3}(g)$

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

Mark the incorrect statement.
a) Alloys with required properties can be made.
b) Alloys have properties different from constituent metals.
c) Alloys can never have carbon in it.
d) Alloy is a heterogenous mixture.

  1. a, b

  2. c, d

  3. a, c

  4. b, d
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Alloys have properties which can different from the constituent metals. In fact it is possible to make alloys having required properties.

Alloy is a homogeneous mixture. Steel is an alloy of iron and carbon.

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

Steel is heated to the very high temperature and then plunged into cold water. This process is called _______.

  1. tempering

  2. anodising

  3. regulating

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

Annealing is the process of heating the steel to high temperature to soften it and it undergoes three phases. Quenching involves heating the steel and tempering in water or oil. This rapid cooling results in hard and brittle steel.