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प्रश्न
The major ore of aluminium is known as:
(a) cinnabar
(b) calamine
(c) bauxite
(d) pyrolusite
उत्तर
(c) bauxite
Bauxite is one of the major ores of aluminium. Its compound is aluminium oxide (Al2O3.2H2O).
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संबंधित प्रश्न
Name two metals which are always found in combined state.
Rock salt is an ore of one of the following metals. This metal is:
(a) Mn
(b) Na
(c) Fe
(d) Cu
State one observation for each of the following :
Copper sulphate solution is electrolysed using copper electrodes.
Name the following:
The process of heating a substance very strongly in such a way that it does not combine with oxygen.
Name the following:
The process in which an ore is heated in air so that oxygen gets added to it to form the oxides.
Compare the process of calcination and roasting.
Complete the incomplete statement with missing words:
Metals are ______ while non-metals are ______ conductors of heat.
How many valence electrons are present in metals ?
Name a non- metal that has a metallic luster and sublimes on heating.
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.
