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प्रश्न
Explain the following methods to protect metals from corrosion:
Passivation
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उत्तर
Passivation: The surface of metal is treated with strong oxidizing acid such as concentrated nitric acid and a thin preventive layer of oxide is formed on the surface of metal. Thus, the surface is made inactive. This is process is called as passivation.
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संबंधित प्रश्न
Write the names and chemical formulae of any one ore of zinc.
Write the names and chemical formulae of any one ore of iron.
What is the chemical composition of malachite?
- CuO . CuC03
- Cu(OH)2 CuC03
- CuO.Cu(OH)2
- Cu2O . Cu(OH)2
Mention names and formulae of two ores of alumunium.
Purification of aluminium by electrolytic refining is carried out by
(a)Hoope process
(b)Hall process
(c)Baeyer process
(d)Serperck process
What is the role of cryolite in the extraction of aluminium?
What is the role of silica in the extraction of copper?
Name the method used for refining of copper metal.
Write the names and chemical formulae of any ‘two’ minerals of aluminium.
What is 'copper matte' ?
What happens when a nickel rod is dipped into a copper sulphate solution? Justify your answer.
[\[\ce{E{^{\circ}_{Ni^{+2}/Ni}}}\] = − 0.25 V and \[\ce{E{^{\circ}_{Cu^{+2}/Cu}}}\] = +0.34 V]
How will you convert the following:
[Ag(CN)2]− to Ag
Bauxite has the composition
Give the uses of zinc.
Metals which occur in their native state in nature:
Metal which is found in free state is:
Carbonate ore of iron is ____________.
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) \[\ce{CaO + SiO2 -> CaSiO3}\]
Although carbon and hydrogen are better reducing agents but they are not used to reduce metallic oxides at high temperatures. Why?
In the thermite process, the reducing agent is:
Which of the following is not ore of aluminium?
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 | ||
| 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 option given below.
Calamine and Malachite, respectively, are the ores of ______.
