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प्रश्न
In electrolytic reduction of alumina _______ is used as a cathode.
पर्याय
sulphur
graphite
platinum
aluminium
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उत्तर
In electrolytic reduction of alumina graphite is used as a cathode.
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संबंधित प्रश्न
Give a reasons for the following:
Carbonate and sulphide ores are usually converted into oxides during the process of extraction of metals.
Name the gas in air which tarnishes silver articles slowly.
Name one metal which is extracted by:
Reduction with heat alone.
Name one ore of copper (other than cuprite). Which compound of copper is present in this ore? Also, write its chemical formula.
Which of the following reactants are used to carry out the thermite reaction required for welding the broken railway tracks?
An element A which is a part of common salt and kept under kerosene reacts with another element B of atomic number 17 to give a product C. When an aqueous solution of product C is electrolysed then a compound D is formed and two gases are liberated.
- What are A and B?
- Identify C and D.
- What will be the action of C on litmus solution? Why?
- State whether element B is a solid, liquid or gas at room temperature.
- Write formula of the compound formed when element B reacts with an element E having atomic number 5.
Some metallic oxides can be reduced by hydrogen, carbon and carbon monoxide and some cannot. Explain.
State why aluminium is extracted from its oxide by electrolysis while copper, lead, iron by reducing agents and mercury and silver by thermal decomposition.
Answer the following questions based on the extraction of aluminium from alumina by Hall - Heroult’s Process :
Why is powdered coke sprinkled on top of the electrolyte?
The following questions relate to the extraction of aluminium by electrolysis.
Explain why it is necessary to renew the anode periodically.
Complete the incomplete statement with missing words:
Metals are ______ while non-metals are ______ conductors of heat.
Which one of the following is not true of metal :
Metals are malleable and ductile
Choose the correct answer from the options given below:
The metal is a liquid at room temperature.
State three objectives achieved during the roasting of ores.
Usually ______ ores are subjected to ______ which is done in the absence of air.
In extraction of copper, the flux used is ____________.
Which of the following ore is concentrated by the Froth floatation process?
Which of the following metals exist in their native state in nature?
- Cu
- Au
- Zn
- Ag
On the basis of reactivity metals are grouped into three categories:
- Metals of low reactivity
- Metals of medium reactivity
- Metals of high reactivity
Therefore metals are extracted in pure form from their ores on the basis of their chemical properties.
Metals of high reactivity are extracted from their ores by electrolysis of the molten ore.
Metals of low reactivity are extracted from their sulphide ores, which are converted into their oxides. The oxides of these metals are reduced to metals by simple heating.
(a) Name the process of reduction used for a metal that gives vigorous reaction with air and water both.
(b) Carbon cannot be used as a reducing agent to obtain aluminium from its oxide? Why?
(c) Describe briefly the method to obtain mercury from cinnabar. Write the chemical equation for the reactions involved in the process.
OR
(c) Differentiate between roasting and calcination giving chemical equation for each.
