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प्रश्न
What is meant by concentration of ores?
उत्तर
The set of processes used to remove as much of gangue as possible, is known as concentration of ores. It is also known as 'ore dressing'.
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संबंधित प्रश्न
Name one ore of mercury. Which mercury compound is present in this ore? Write its chemical formula.
During galvanisation, iron metal is given a thin coating of one of the following metals. This metal is:
(a) chromium
(b) tin
(c) zinc
(d) copper
Distinguish between ‘roasting’ and ‘calcination’. Which of these two is used for sulphide ores and why?
Give the chemical formula of :
Sodium aluminate
Define the term : Gangue
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 ______.
Which one of the following is not true of metal :
Metals are malleable and ductile
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 ______.
Answer the questions on the following passage.
The minerals from which the metal can be separated economically are called ores. Ores contain many types of impurities such as soil, sand and rocky substances along with metal compounds. These impurities are called gangue.
Metals can be extracted from their ores by means of various methods of separation. The process of extraction of metal in a pure state from the ores is also a part of metallurgy.
Ores are taken out from the mines and the gangue is usually separated from the ore at the site itself by various methods. Then the ores are carried out to the place where metals are produced. Here metals are extracted in pure form. Then metals are further purified by different methods of purification. This entire process is called metallurgy. Most metals being reactive do not occur in nature in the free state but are found in combined state as their salts such as oxides, carbonates, sulphides, and nitrates. however, the most unreactive metals that are not affected by air, water and other natural factors like silver, gold, platinum, generally occur in a free state. The compounds of metals that occur in nature along with the impurities are called minerals.
- What are ores?
- Which processes are involved in the branch of metallurgy? What is metallurgy?
- Which metals are found in a free state?
- In what forms are metals found in combined state?
- What is gangue?
Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2. What steps will you take to convert them into metals?
