Class 12 Chemistry
General Principles and Processes of Isolation of Elements
Q.1
Copper can be extracted by hydrometallurgy but not zinc. Explain.
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Q.2
What is the role of depressant in froth floatation process?
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Q.3
Why is the extraction of copper from pyrites more difficult than that from its
oxide ore through reduction?
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Q.4
Explain: (i) Zone refining
(ii) Column chromatography.
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Q.5
Out of C and CO, which is a better reducing agent at 673 K?
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Q.6
Name the common elements present in the anode mud in electrolytic refining of copper. Why are they so present?
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Q.7
Write down the reactions taking place in different zones in the blast furnace
during the extraction of iron.
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Q.8
Write chemical reactions taking place in the extraction of zinc from zinc blende
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Q.9
State the role of silica in the metallurgy of copper?
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Q.10
What is meant by the term “chromatography”?
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Q.11
What criterion is followed for the selection of the stationary phase in
chromatography?
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Q.12
Describe a method for refining nickel.
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Q.13
How can you separate alumina from silica in a bauxite ore associated with silica? Give equations, if any.
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Q.14
Giving examples differentiate between ‘roasting’ and ‘calcination’.
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Q.15
How is ‘cast iron’ different from ‘pig iron”?
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Q.16
Differentiate between “minerals” and “ores”.
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Q.17
Why copper matte is put in silica lined converter?
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Q.18
What is the role of cryolite in the metallurgy of aluminium?
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Q.19
How is leaching carried out in case of low grade co pper ores?
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Q.20
Why is zinc not extracted from zinc oxide through reduction using CO?
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Q.21
The value of ΔfG0 for formation of Cr 2O3 is – 540 kJmol −1 and that of Al 2O3 is –827 kJmol−1. Is the reduction of Cr 23+ possible with Al?
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Q.22
Out of C and CO, which is a better reducing agent for ZnO?
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Q.23
The choice of a reducing agent in a particular case depends on thermodynamic
factor. How far do you agree with this statement? Support your opinion with
two examples.
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Q.24
Name the processes from which chlorine is obtained as a by -product. What will
happen if an aqueous solution of NaCl is subjected to electrolysis?
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Q.25
What is the role of graphite rod in the electrometallurgy of aluminium?
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Q.26
Outline the principles of refining of metals by the following methods:
(i) Zone refining
(ii) Electrolytic refining
(iii) Vapour phase refining?
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Q.27
Predict conditions under which Al might be expected to re duce MgO.
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