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प्रश्न
Although carbon and hydrogen are better reducing agents but they are not used to reduce metallic oxides at high temperatures. Why?
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उत्तर
It is because at high temperature carbon and hydrogen react with metals to form carbides and hydrides respectively.
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संबंधित प्रश्न
Fe2O3 is reduced to spongy iron near the top of blast furance by
(A) H2
(B) CaO
(C) SiO2
(D) CO
Differentiate between “minerals” and “ores”.
Explain the following methods to protect metals from corrosion:
Passivation
Why does copper obtained in the extraction from copper pyrites have a blistered appearance?
Describe the role of the cryolite in the extraction of aluminium from pure alumina.
Bauxite has the composition
The most abundant metal on earth is:
The sulphide ore of iron is ____________.
Carbonate ore of iron is ____________.
Which of the following options are correct?
(i) Cast iron is obtained by remelting pig iron with scrap iron and coke using hot air blast.
(ii) In extraction of silver, silver is extracted as cationic complex.
(iii) Nickel is purified by zone refining.
(iv) Zr and Ti are purified by van Arkel method.
In the extraction of aluminium by Hall-Heroult process, purified \[\ce{Al2O3}\] is mixed with \[\ce{CaF2}\] to:
(i) lower the melting point of \[\ce{Al2O3}\].
(ii) increase the conductivity of molten mixture.
(iii) reduce \[\ce{Al^{3+}}\] into \[\ce{Al(s)}\].
(iv) acts as catalyst.
Which of the following reactions occur during calcination?
(i) \[\ce{CaCo3 -> CaO + CO2}\]
(ii) \[\ce{2FeS2 + 11/2 O2 -> Fe2O3 + 4SO2}\]
(iii) \[\ce{Al2O3. {x}H2O -> Al2O3 + {x}H2O}\]
(iv) \[\ce{ZnS + 3/2 O2 -> ZnO + SO2}\]
The main reactions occurring in blast furnace during extraction of iron from haematite are:
(i) \[\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}\]
(ii) \[\ce{FeO + SiO2 -> FeSiO3}\]
(iii) \[\ce{Fe2O3 + 3C -> 2Fe + 3CO}\]
(iv) \[\ce{CaO + SiO2 -> CaSiO3}\]
Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.
Identify a mineral for the major source of boron from the following list?
In the electrolytic process for the extraction of aluminium the electrolyte is:-
Native silver metal forms a water solution complex with dilute solution of Na CN in the presence of
The ore that contains both iron and copper is ______.
