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प्रश्न
Explain the following methods to protect metals from corrosion:
Galvanization
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उत्तर
Galvanization:
1) The rusting of iron can be prevented by coating the metal surface with another metal such as zinc, that is oxidized in preference to iron. This process is called galvanization.
2) If the zinc layer is scratched, even then it protects iron from corrosion as long as Fe and Zn are in contact. If Fe is oxidized to Fe2+, then Zn immediately reduces Fe2+ back to Fe.
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संबंधित प्रश्न
Write the names and chemical formulae of any one ore of iron.
The process of leaching alumina, using sodium carbonate is called
- Bayer's process
- Decomposition
- Cyanide process
- Hall's process
Write the reactions involved in the zone of reduction in blast furnace during extraction of iron.
Fe2O3 is reduced to spongy iron near the top of blast furance by
(A) H2
(B) CaO
(C) SiO2
(D) CO
Mention names and formulae of two ores of alumunium.
What is the role of cryolite in the extraction of aluminium?
Indicate the principle behind the method used for the refining of zinc.
Which form of the iron is the purest form of commercial iron?
Write the names and chemical formulae of any ‘two’ minerals of aluminium.
Which among the following minerals does NOT contain aluminium?
(a) Cryolite
(b) Siderite
(c) China clay
(d) Corundum
Explain the following methods to protect metals from corrosion:
Passivation
The chemical formula of willemite is __
(a) ZnS
(b) ZnCO3
(c) ZnO
(d) Zn2SiO4
What is 'copper matte' ?
What is the role of the following compound-
SiO2 in the extraction of copper from copper pyrites?
Metal which is found in free state is:
Which among the following statement is correct?
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) \[\ce{ZnS + 3/2 O2 -> ZnO + SO2}\]
Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.
Native silver metal forms a water solution complex with dilute solution of Na CN in the presence of
Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
Pyrolusite is ______.
Match List - I with List - II.
| List - I | List - II | ||
| (One) | (Composition) | ||
| (A) | Siderite | (I) | FeCO3 |
| (B) | Malachite | (II) | CuCO3 · Cu(OH)2 |
| (C) | Sphalerite | (III) | ZnS |
| (D) | Calamine | (IV) | ZnCO3 |
Choose the correct answer from the options given below:
Calamine and Malachite, respectively, are the ores of ______.
