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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
What is the chemical composition of malachite?
- CuO . CuC03
- Cu(OH)2 CuC03
- CuO.Cu(OH)2
- Cu2O . Cu(OH)2
Silica is added to roasted copper ore during smelting process to remove _______.
(A) ferrous sulphide
(B) ferrous oxide
(C) cuprous sulphide
(D) cuprous oxide
Fe2O3 is reduced to spongy iron near the top of blast furance by
(A) H2
(B) CaO
(C) SiO2
(D) CO
Draw neat and labelled diagram of Bessermer converter used in the extraction of copper.
In the extraction of Al, impure Al2O3 is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?
Describe the roles of the following: SiO2 in the extraction of copper from copper matte
Which of the ores mentioned can be concentrated by magnetic separation method?
Differentiate between “minerals” and “ores”.
Which among the following minerals does NOT contain aluminium?
(a) Cryolite
(b) Siderite
(c) China clay
(d) Corundum
The chemical formula of willemite is __
(a) ZnS
(b) ZnCO3
(c) ZnO
(d) Zn2SiO4
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]
Bauxite has the composition
What are the differences between minerals and ores?
The most abundant metal on earth 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) \[\ce{ZnS + 3/2 O2 -> ZnO + SO2}\]
Identify a mineral for the major source of boron from the following list?
Extraction of zinc from zinc blende is achieved by:-
When compared to ΔG° for the formation of Al2O3 ΔG° for the formation of Cr2O3 is
Native silver metal forms a water solution complex with dilute solution of Na CN in the presence of
Which of the following is not an ore of magnesiuim?
In the extraction of iron, the slag produce 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 ______.
The ore that contains both iron and copper is ______.
