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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
Write the names and chemical formulae of any one ore of zinc.
The process of leaching alumina, using sodium carbonate is called
- Bayer's process
- Decomposition
- Cyanide process
- Hall's process
Silica is added to roasted copper ore during smelting process to remove _______.
(A) ferrous sulphide
(B) ferrous oxide
(C) cuprous sulphide
(D) cuprous oxide
Out of C and CO, which is a better reducing agent at the lower temperature range in the blast furnace to extract iron from the oxide ore?
Fe2O3 is reduced to spongy iron near the top of blast furance by
(A) H2
(B) CaO
(C) SiO2
(D) CO
What is the role of CO in the extraction of Iron?
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?
What is the role of silica in the extraction of copper?
Which form of the iron is the purest form of commercial iron?
Describe the roles of the following: SiO2 in the extraction of copper from copper matte
The chemical formula of willemite is __
(a) ZnS
(b) ZnCO3
(c) ZnO
(d) Zn2SiO4
What is 'copper matte' ?
Copper has the face centred cubic structure. The coordination number of each ion is:
In the extraction of zinc from zinc blende:
(i) Give an equation to show how zinc oxide is converted to zinc.
(ii) How is impure zinc finally electro-refined?
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: ___________
What happens when a nickel rod is dipped into a copper sulphate solution? Justify your answer.
`[E_((Ni^(+2))/(Ni))^0 = -0.25"v" and E _(("Cu"^(+2))/("Cu"))^0 = +0.34"v"]`
Bauxite has the composition
Give the uses of zinc.
Metal which is found in free state is:
Carbonate ore of iron is ____________.
When a strip of metallic zinc is placed in an aqueous solution of copper nitrate the blue colour of the solution disappear due to formation of
In the thermite process, the reducing agent is:
In the electrolytic process for the extraction of aluminium the electrolyte is:-
When compared to ΔG° for the formation of Al2O3 ΔG° for the formation of Cr2O3 is
In the extraction of iron, the slag produce is
Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
Pyrolusite is ______.
