Ores and Metallurgy MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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81.
Which of the following statements is correct ?
(i) Copper is extracted by hydrometallurgy from low grade ores.
(ii) In electrolytic reduction of alumina, graphite is acting as anode and steel vessel with lining of carbon acts as cathode.
(iii) In Hall-Heroult process, aluminium is obtained at anode and $$CO$$ and $$C{O_2}$$ are produced at cathode.
82.
Which of the following statements are incorrect ?
(i) Zinc can be extracted by self-reduction.
(ii) A depressant prevents certain type of particles to come to the froth.
(iii) Copper matte contains $$ZnS$$ and $$C{u_2}S.$$
(iv) The solidified copper obtained from reverberatory furnace has blistered appearance due to evolution of $$S{O_2}$$ during the extraction.
A
(i) and (ii)
B
(ii) and (iii)
C
(i) and (iii)
D
(ii) and (iv)
Answer :
(i) and (iii)
Copper matte consists of $$C{u_2}S$$ and $$FeS.$$
83.
When a metal is to be extracted from its ore and the gangue associated with the ore is silica, then
A
an acidic flux is needed
B
a basic flux is needed
C
both acidic and basic fluxes are needed
D
Neither of them is needed
Answer :
a basic flux is needed
Since silica is acidic impurity the flux must be basic.
$$CaO + Si{O_2} \to CaSi{O_3}$$
84.
During the process of electrolytic refining of copper, some metals present as impurity settle as 'anode mud'. These are
A
$$Sn$$ and $$Ag$$
B
$$Pb$$ and $$Zn$$
C
$$Ag$$ and $$Au$$
D
$$Fe$$ and $$Ni$$
Answer :
$$Ag$$ and $$Au$$
In the electrolytic refining of copper the more electropositive impurities like $$Fe,Zn,Ni,Co,$$ etc. dissolve in the solution and less electropositive impurities such as $$Ag,Au$$ and $$Pt$$ collect below the anode in the form of anodic mud.
85.
In Hall-Heroult process how much carbon anode is burnt away to produce each $$1kg$$ of aluminium?
A
0.3$$\,kg$$
B
0.5$$\,kg$$
C
1$$\,kg$$
D
0.1$$\,kg$$
Answer :
0.5$$\,kg$$
For each $$kg$$ of $$Al$$ produced, about $$0.5\,kg$$ of carbon anode is burnt away.
86.
Which of the following metals cannot be obtained by reduction of its metal oxide by aluminium?
A
$$Cr$$
B
$$Mn$$
C
$$Fe$$
D
$$Mg$$
Answer :
$$Mg$$
Since reduction potential of $$Al$$ is more than that of $$Mg$$ and less than other given metals. So it cannot reduce $$Mg$$ from its oxide.
87.
Which of the following is not an ore of magnesium?
A
Carnallite
B
Magnesite
C
Dolomite
D
Gypsum
Answer :
Gypsum
Gypsum is an ore of calcium and not of magnesium. The structural formula of gypsum is $$CaS{O_4} \cdot 2{H_2}O.$$
88.
Match the column I with column II and mark the appropriate choice.
Column I
Column II
a.
Van Arkel method
1.
$$Ni$$
b.
Zone refining
2.
$$Ti$$
c.
Mond process
3.
$$Ag$$
d.
Cupellation
4.
$$Ge$$
A
a - 1, b - 2, c - 3, d - 4
B
a - 3, b - 1, c - 2, d - 4
C
a - 2, b - 4, c - 1, d - 3
D
a - 4, b - 3, c - 1, d - 2
Answer :
a - 2, b - 4, c - 1, d - 3
No explanation is given for this question. Let's discuss the answer together.
89.
Match the column I with column II and mark the appropriate choice.
Column I
Coumn II
a.
Electrical industry
1.
Zinc
b.
Batteries
2.
Steel
c.
Gutter pipes
3.
Copper
d.
Gas stoves
4.
Cast iron
A
a - 1, b - 2, c - 3, d - 4
B
a - 2, b - 3, c - 4, d - 1
C
a - 4, b - 3, c - 2, d - 1
D
a - 3, b - 1, c - 4, d - 2
Answer :
a - 3, b - 1, c - 4, d - 2
No explanation is given for this question. Let's discuss the answer together.
90.
Extraction of gold and silver involves leaching with $$C{N^ - }$$ $$ion.$$ Silver is later recovered by
A
liquation
B
distillation
C
zone refining
D
displacement with $$Zn$$
Answer :
displacement with $$Zn$$
Extraction of gold and silver involves leaching with $$C{N^ - }$$ $$ion.$$ Silver is later recovered by distillation of $$Zn.$$
In the metallurgy of silver or gold, the respective metal is leached with a dilute solution of $$NaCN$$ or $$KCN$$ in the presence of air to obtain the metal in solution as complex. From the complex, metal is obtained later by replacement.
In general,
$$4M\left( s \right) + 8C{N^ - }\left( {aq} \right) + $$ $$2{H_2}O\left( {aq} \right) + {O_2}\left( g \right) \to $$ $$4{\left[ {M{{\left( {CN} \right)}_2}} \right]^ - }\left( {aq} \right) + 4O{H^ - }\left( {aq} \right)$$
$$2{\left[ {M{{\left( {CN} \right)}_2}} \right]^ - }\left( {aq} \right) + Zn\left( s \right)$$ $$ \to {\left[ {Zn{{\left( {CN} \right)}_4}} \right]^{2 - }}\left( {aq} \right) + 2M\left( s \right)$$
$$M = Ag\,\,{\text{or}}\,Au$$
This method is known as Mac-Arthur Forest cyanide process.