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प्रश्न
Explain the following methods to protect metals from corrosion:
Passivation
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
The process of leaching alumina, using sodium carbonate is called
- Bayer's process
- Decomposition
- Cyanide process
- Hall's process
What is the chemical composition of malachite?
- CuO . CuC03
- Cu(OH)2 CuC03
- CuO.Cu(OH)2
- Cu2O . Cu(OH)2
Write chemical formulae of the following ores :
(a) Calamine
(b) Haematite
(c) Magnetite
(d) Corundum
What is the role of CO in the extraction of Iron?
What is the role of coke in the extraction of iron from its oxides?
Indicate the principle behind the method used for the refining of zinc.
What is the role of silica in the extraction of copper?
Name the method used for refining of copper metal.
Differentiate between “minerals” and “ores”.
Define Leaching.
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:
Galvanization
What is 'copper matte' ?
What is the role of the following compound-
SiO2 in the extraction of copper from copper pyrites?
Complete the following statement by selecting the correct alternative from the choices given:
A current liberates 0.50 g of hydrogen in 2 hours. The weight of copper (at. wt. = 63.5) deposited at the same time by the same current through copper sulphate solution is: ___________
Bauxite has the composition
Give the uses of zinc.
Metal which is found in free state is:
The sulphide ore of iron is ____________.
Carbonate ore of iron is ____________.
When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains ______.
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.
Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.
Which of the following is not ore of aluminium?
When compared to ΔG° for the formation of Al2O3 ΔG° for the formation of Cr2O3 is
Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
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.
