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प्रश्न
Explain the concept of Roasting.
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उत्तर
In roasting process, the sulphide ores are strongly heated in air to transform them into oxides. In this process, sulphide ores are oxidized to form metal oxides and sulphur dioxide gas.
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संबंधित प्रश्न
Name the following:
Main ore of aluminium.
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?
Name two metals which are highly resistant to corrosion.
Fill in the following blank with suitable word:
The non-metal present in steel is ............
Why does aluminium not corrode right through?
Which metal is extracted from cinnabar ore?
How is sodium metal extracted? Explain with the help of equation of the reaction involved.
Describe the extraction of zinc metal from its sulphide ore (zinc blende). Write equations of the reactions involved.
In an electrolytic tank, aluminium metal is being extracted by the electrolysis of molten aluminium oxide using carbon electrodes. It is observed that one of the carbon electrodes is gradually burnt away and has to be replaced.
(a) Which carbon electrode (cathode or anode) is burnt away?
(b) Why is this carbon electrode burnt away?
A black metal oxide XO2 is used as a catalyst in the preparation of oxygen gas from potassium chlorate. The oxide XO2 is also used in ordinary dry cells. The metal oxide XO2 cannot be reduced satisfactorily with carbon to form metal X.
(a) Name the metal X.
(b) Name the metal oxide XO2.
(c) Which reducing agent can be used to reduce XO2 to obtain metal X?
(d) Name another metal which can also be extracted by the reduction of its oxide with the above reducing agent.
Give the chemical formula of :
Bauxite
Name the following:
The process of heating a substance very strongly in such a way that it does not combine with oxygen.
What is meant by concentration of ores?
Compare the process of calcination and roasting.
What is passive iron?
Heating an ore in a limited supply of air or in the absence of air at a temperature just below its melting point is known as ______.
Complete the following by selecting the correct option from the choices given:
The metal which does not react with water or dilute H2SO4 but reacts with concentrated H2SO4 is _________
Explain the following reaction with the balanced equation.
Zinc oxide is treated with carbon
Explain concept with example/explain with the help of a balanced equation.
Calcination
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.
