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प्रश्न
In the extraction of aluminium: Why is it necessary to replace anodes time to time?
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उत्तर
The anode is replaced from time to time because it gets oxidised by oxygen which evolves at it.
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संबंधित प्रश्न
Define the Ore.
What chemical process is used for obtaining a metal from its oxide?
Metallic oxides of zinc, magnesium and copper were heated with the following metals.
| Metal | Zinc | Magnesium | Copper |
| Zinc oxide | – | – | – |
| Magnesium oxide | – | – | – |
| Copper oxide | – | – | – |
In which cases will you find displacement reactions taking place?
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset, but after a futile argument, the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper.
The process by which sulphide ore is concentrated.
Name a reducing agent that may be used to obtain manganese from manganese dioxide.
Why do gold ornaments look new even after several years of use?
Explain given equation, what happens when ZnCO3 is heated in the absence of air?
Name the gas produced when calamine ore is calcined.
Give the name of one ore of iron. Which iron compound is present in this ore? Write its chemical formula.
The articles made of silver metal become dark on prolonged exposure to air. This is due to the formation of a layer of its:
(a) oxide
(b) hydride
(c) sulphide
(d) carbonate
The metal which can be extracted from pyrolusite ore is:
(a) mercury
(b) manganese
(c) aluminium
(d) magnesium
Aluminum is used in thermite welding:
what is ignition mixture?
Aluminum is used in thermite welding:
write reaction for process?
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?
Name the ore of mercury. With the help of balanced chemical equations, explain the process of extraction of mercury from its ore.
Define the term:
Slag
What is passive iron?
Explain the characteristics of ionic compounds.
