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प्रश्न
What is meant by galvanisation? Why is it done?
उत्तर
Galvanisation is a process wherein a thin layer of zinc metal gets deposited on iron objects. This is done to prevent rusting of iron by protecting it to come in contact with air and moisture. Zinc metal, being more reactive, reacts with air to form hard layer of zinc oxide, which prevents air from passing through it.
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संबंधित प्रश्न
Name the metal which is used for galvanising iron.
Explain why, iron sheets are coated with zinc.
Fill in the following blank with suitable word:
The corrosion of copper produces a .............. coating of basic copper carbonate on its surface
What is meant by 'rusting of iron'? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.
A metal X which is resistant to corrosion is produced by the electrolysis of its molten oxide whereas another metal Y which is also resistant to corrosion is produced by the reduction of its oxide with carbon. Metal X can be used in powder form in thermite welding whereas metal Y is used in making cathodes of ordinary dry cells.
(a) Name the metals X and Y.
(b) Which of the two metals is more reactive : X or Y?
(c) Name one ore or metal X. Also write its chemical formula.
(d) Name one ore or metal Y. Also write its chemical formula.
(e) Name one alloy of metal X and one alloy of metal Y.
Four metals P, Q, R and S are all obtained by the reduction of their oxides with carbon. Metal P is used to form a thin layer over the sheets of metal S to prevent its corrosion. Metal Q is used for electroplating tiffin boxes made of metal S whereas metal R is used in making car batteries. Metals Q and R form an alloy called solder. What are metals P, Q, R and S? How have you arrived at this conclusion?
State under what conditions corrosion is faster ?
Corrosion can be an advantage in some case.Explain ?
Explain with reason:
Roasting is carried out on sulphide ores and not on carbonate ores.
Identify the process shown in the diagram and explain it in short
What is done to prevent corrosion of metals?
What is "rusting"? Describe with a labelled diagram an activity to investigate the conditions under which iron rusts.
Give reason.
Copper and brass utensils should be tinned.
Write a short note on Alloying.
Stainless steel is an alloy of _______.
Identify the correct statement from the following:
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Explain the chemical reactions in rusting of iron.
