ICSE
CLASS
10
Previous
Year Questions
METALLURGY
Q1. Choose from the list of substances, as to what matches the description:
[Acetylene
gas, aqua fortis, coke, brass, barium chloride, bronze, platinum]
(i)
The
substance is an alloy of zinc, copper and tin. [2011][1]
Show Answer
Ans. Bronze
Q2. Choose the correct answer from the options given below:
(i)
This
metal is a liquid at room temperature. [2011][1]
a.
Potassium
b.
Zinc
c.
Gold
d.
Mercury
Show Answer
Ans. d. Mercury
(ii)
The
metals zinc and tin are present in the alloy: [2013][1]
a.
Solder
b.
Brass
c.
Bronze
d.
Duralumin
Show Answer
Ans. c. Bronze
(iii)
The
main ore used for the extraction of iron is:
[2014][1]
a.
Haematite
b.
Calamine
c.
Bauxite
d.
Cryolite
Show Answer
Ans. a. Haematite
(iv)
This
is not an alloy of copper: [2015][1]
a.
Brass
b.
Bronze
c.
Solder
d.
Duralumin
Show Answer
Ans. c. Solder
(v)
The
two main metals in bronze are: [2016][1]
a.
Copper
and zinc
b.
Copper
and lead
c.
Copper
and nickel
d.
Copper
and tin
Show Answer
Ans. d. Copper and tin
(vi)
The
reason for using Aluminium in the alloy duralumin
is :
a.
Aluminium
is brittle.
b.
Aluminium
gives strength.
c.
Aluminium
brings lightness.
d.
Aluminium
lowers melting point.
Show Answer
Ans. c. Aluminium brings lightness.
Q3. Name the following:
(i)
A
metal present in cryolite other than sodium. [2012][1]
Show Answer
Ans. Aluminium
(ii)
A
metal which is unaffected by dilute or concentrated acids. [2012][1]
Show Answer
Ans. Gold
(iii)
A
compound added to lower the fusion temperature of
electrolytic bath in the extraction of aluminium. [2014][1]
Show Answer
Ans. Cryolite (Na3AlF6)
(iv)
The
ore of zinc containing its sulphide. [2014][1]
Show Answer
Ans. Zinc Blende (ZnS)
(v)
An
alloy of lead and tin that is used in electrical circuits. [2017][1]
Show Answer
Ans. Fuse metal/Solder
(vi)
The
most common ore of iron is _______.
(calamine/haematite) [2018][1]
Show Answer
Ans. Haematite
(vii)
The
substance prepared by adding other metals to a
base metal in appropriate proportions to obtain certain desirable properties.
[2020][1]
Show Answer
Ans. Alloy
(viii)
An
alloy used to make statues is ___________ .
(bronze, brass, fuse metal) [2020][1]
Show Answer
Ans. Bronze
(ix)
A
trivalent metal used to make light tools. [2020][1]
Show Answer
Ans. Aluminium
(x)
A
monovalent non-metal present in fluorspar. [2020][1]
Show Answer
Ans. Fluorine
Q4. Name
the
metal which is found abundantly in the earth’s crust. [2011][1]
Show Answer
Ans. Aluminium
Q5. Write
the
chemical formulae of one main ore of iron and aluminium. [2011][1]
Show Answer
Ans. One main ore of iron is Haematite (Fe2O3) and that of aluminium is bauxite (Al2O3.2H2O).
Q6. Write
the
constituents of electrolyte for the extraction of aluminium. [2011][1]
Show Answer
Ans. Alumina (20%), cryolite (60%), fluorspar (20%).
Q7. Match
the
properties and uses of alloys in List 1 with the appropriate answer from List
2. [2012][5]
|
List
1 |
List
2 |
|
1. The
alloy contains Cu and Zn, is hard, silvery and
is used in decorative articles.
2. It
is stronger than Aluminium, light and is used in
making light tools.
3. It
is lustrous, hard, corrosion resistant and used
in surgical instruments.
4. Tin
lowers the melting point of the alloy and is
used for soldering purpose.
5. The
alloy is hard, brittle, takes up polish and is
used for making statues. |
A. Duralumin
B. Brass
C. Bronze
D.Stainless
steel
E. Solder
|
Show Answer
Ans.
1. C. Brass
2. A. Duralumin
3. D. Stainless steel
4. E. Solder
5. C. Bronze
Q8. The
following questions are relevant to the extraction of Aluminium: [2012][3]
(i)
State
the reason for addition of caustic alkali to bauxite ore during purification of
bauxite.
Show Answer
Ans. On adding caustic alkali to bauxite, bauxite dissolves in it and forms sodium meta aluminate because of the amphoteric nature of aluminium, leaving behind insoluble impurities called red mud, which can be removed by filtration. This is why, caustic alkali is added to bauxite.
(ii)
Give
a balanced chemical equation for the above reaction.
Show Answer
Ans. Al2O3.2H2O + 2NaoH -------> 2NaAlO2 + 3H2O
(iii)
Along
with cryolite and alumina, another substance is
added to the electrolytic mixture. Name the substance and give one reason for
the addition.
Show Answer
Ans. Fluorspar is added to lower the high melting point of alumina and increase conductivity.
Q9. The
following questions relate to the extraction of aluminium by electrolysis:
[2013][4]
(i)
Name
the other aluminium containing compound added to alumina and state its
significance.
Show Answer
Ans. Cryolite. It lowers the fusion temperature from 2050°C to 950°C and enhances conductivity.
(ii)
Give
the equation for the reaction that takes place at the cathode.
Show Answer
Ans. 4Al3+ + 12e- ---------> 4Al
(iii)
Explain
why is it necessary to renew the anode
periodically.
Show Answer
Ans. It is necessary to renew the anode periodically because it gets oxidized by the oxygen evolved at the anode.
Q10. State
the
main components of the following alloys: [2014][3]
(i)
Brass
[2018]
Show Answer
Ans. Copper and Zinc
(ii)
Duralumin
[2018]
Show Answer
Ans. Aluminium, Copper, Magnesium and Manganese
(iii)
Bronze
Show Answer
Ans. Copper and Tin
Q11. For
each of
the substance listed below, describe the role played in the extraction of
aluminium: [2015][3]
1. Cryolite
Show Answer
Ans. It acts as a solvent and lowers the fusion temperature from 2050°C to 950°C and enhances conductivity.
2. Sodium
hydroxide
Show Answer
Ans. It is used to remove insoluble impurities from the ore. On adding sodium hydroxide to bauxite, bauxite dissolves in it and forms sodium meta aluminate because of the amphoteric nature of aluminium, leaving behind insoluble impurities called red mud, which can be removed by filtration.
3. Graphite
Show Answer
Ans. It is an electrode in the extraction of aluminium because it has a very high melting point and is a good conductor of electricity.
Q12. Explain
why: [2015][1]
(i)
In
the electrolysis of alumina using the Hall
Heroult’s process the electrolyte is covered with powered coke.
Show Answer
Ans. To reduce the heat loss by radiation and to prevent burning of anode.
Q13.
[2016][5]
(i) Name
the solution used to react with Bauxite as a
first step in obtaining pure aluminium oxide, in the Baeyer’s process.
Show Answer
Ans. Sodium hydroxide (NaOH)
(ii) Write
the equation for the reaction where the
aluminium oxide for the electrolytic extraction of aluminium is obtained by
heating aluminium hydroxide.
Show Answer
Ans. 2Al(OH)3------heat 1000°C---> Al2O3 + 3H2
(iii) Name
the compound added to pure alumina to lower the fusion temperature during the
electrolytic reduction of alumina.
Show Answer
Ans. Cryolite
(iv) Write the equation for the reaction that occurs at the cathode during the extraction
of aluminium by electrolysis.
Show Answer
Ans. 4Al3+ +12e- -----> 4Al
(v) Explain
why it is preferable to use a number of
graphite electrodes as anode instead of a single electrode, during the above
electrolysis.
Show Answer
Ans. During the above electrolysis, oxygen is evolved at the anode, which reacts with the carbon in the graphite to form carbon dioxide, consuming the anode slowly. Therefore, it is preferable to use a number of graphite electrodes as anode instead of a single one.
Q14. Answer
the
following questions with respect to the electrolytic process in the extraction
of aluminium: [2017][3]
(i)
Identify
the components of the electrolyte other than pure alumina and the role played
by each.
Show Answer
Ans.
Cryolite
and fluorspar.
Cryolite lowers the fusion temperature
of alumina from 2050°C to 950°C and enhances conductivity.Fluorspar acts
as a solvent and enhances conductivity.
(ii)
Explain
why powdered coke is sprinkled over the electrolytic mixture.
Show Answer
Ans. It reduces heat loss by radiation and prevents burning of the anode.
Q15.
[2018][4]
(i)
Name
the most common ore of the metal aluminium from which the metal is extracted.
Write the chemical formula of the ore.
Show Answer
Ans. Bauxite (Al2O3.2H2O)
(ii)
Name
the process by which impure ore of aluminium gets purified by using
concentrated solution of an alkali.
Show Answer
Ans. Baeyer’s process
(iii)
Write
the equation for the formation of aluminium at
the cathode during the electrolysis of alumina.
Show Answer
Ans. 4Al3+ +12e- ------> 4Al
Q16. Give
the
chemical formula of: [2019][2]
(i)
Bauxite
Show Answer
Ans. Al2O3.2H2O
(ii)
Cryolite
Show Answer
Ans. Na3AlF6
Q17. Answer
the following
question based on the extraction of aluminium from alumina by Hall-Heroult’s
process: [2019][3]
(i)
What
is the function of cryolite used along with alumina as the electrolyte?
Show Answer
Ans. Cryolite lowers the fusion temperature of alumina from 2050°C to 950°C and enhances conductivity.
(ii)
Why
is powdered coke sprinkled on top of the electrolyte?
Show Answer
Ans. It reduces heat loss by radiation and prevents burning of the anode.
(iii)
Name
the electrode, from which aluminium is collected.
Show Answer
Ans. Cathode which is carbon lining covering the inside portion of the vessel.
Q18. Match
the
alloys given in column I to the uses given in column II. [2019][4]
|
Column
I |
Column
II |
|
(i)
Duralumin
(ii)
Solder
(iii)
Brass
(iv)
Stainless
Steel |
A. Electrical
fuse
B. Surgical
instrument
C. Aircraft
body
D. Decorative
articles |
Show Answer
(i)
C.
(ii)
A.
(iii)
D.
(iv)
B.
Q19. Baeyer’s
process is used to concentrate bauxite ore to alumina. Give balanced chemical
equations for the reaction taking place for its conversion from bauxite to
alumina. [2020][3]
Show Answer
NaAlO2
+ 2H2O --------à
NaOH + Al(OH)3
2Al(OH)3
----heat 1000°C----à
Al2O3 + 3H2O
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