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प्रश्न
Define roasting.
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उत्तर
Roasting is the process of heating concentrated ore to a high temperature in the presence of air. The process is usually carried out for sulphide ores.
संबंधित प्रश्न
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?
M is a metal above hydrogen in the activity series and its oxide has the formula M2O. This oxide when dissolved in water forms the corresponding hydroxide which is a good conductor of electricity. In the above context, answer the following:
1) What kind of combination exists between M and O?
2)How many electrons are there in the outermost shell of M?
3) Name the group to which M belongs.
4) State the reaction taking place at the cathode.
5) Name the product at the anode.
Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.
Why do gold ornaments look new even after several years of use?
Name one metal which is extracted by:
Reduction with carbon.
Name two metals which are found in nature mainly in the free state (as metallic elements).
Which metal is extracted from cinnabar ore?
Which gas is produced during the extraction of aluminium? At which electrode is this gas produced?
Give the name of one ore of iron. Which iron compound is present in this ore? Write its chemical formula.
An ore of manganese metal is ______.
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.
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- 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.
State three objectives achieved during the roasting of ores.
State why aluminium is extracted from its oxide by electrolysis while copper, lead, iron by reducing agents and mercury and silver by thermal decomposition.
What is passive iron?
Write equations for each of the above metal which reacts with water.
Name : The metal which is liquid at room temperature.
X is an element in the form of a powder. X burns in oxygen and the product is soluble in water. The solution is tested with litmus. Write down only the word which will correctly complete each of the following sentences:
(a) If X is a metal, then the litmus will turn ______.
(b) If X is a non-metal, then the litmus will turn ______.
(c) If X is a reactive metal, then ______ will be evolved, when X reacts with dilute sulphuric acid.
(d) If X is a non -metal, it will form _ oxide, which will form ______ solution with water.
(e) If X is a non -metal, it will not conduct electricity unless it is carbon in the form of ______.
Name a non- metal that has a metallic luster and sublimes on heating.
How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle? Why can the same process not be applied for them? Name the process used for the extraction of these metals.
Sulphide ores : Roasting : : Carbonate ores : _______
Find the odd one out and give its explanation.
Write the name.
Extraction of aluminium from alumina-
Bauxite reacts with sodium hydroxide in the Bayer’s process.
Write the molecular formulae of the following compound.
Cryolite
Explain the concept of Calcination.
The highly reactive metals like Sodium, Potassium, Magnesium, etc. are extracted by the ____________.
Electrical wires have a coating of an insulting material. The material, generally used is
Give the reaction involved during extraction of zinc from its ore by
- roasting of zinc ore
- calcination of zinc ore
