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प्रश्न
Why does aluminium not corrode right through?
उत्तर
Aluminium is a highly reactive metal. It reacts easily with oxygen in the air and forms a layer of aluminium oxide on its surface. This layer is very tough and does not allow air to enter the metal for further reaction. This prevents aluminium from further corrosion. Thus, aluminium articles become unreactive toward air and water and do not corrode easily due to the presence of strong aluminium oxide layer on it. Hence, aluminium is highly resistive to corrosion.
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संबंधित प्रश्न
In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Name two metals which are always found in combined state.
An ore of manganese metal is:
(a) bauxite
(b) haematite
(c) cuprite
(d) pyrolusite
Manganese metal is extracted from manganese dioxide by a reduction process by making use of:
(a) carbon
(b) hydrogen
(c) electrolysis
(d) aluminium
Define the following term.
Gangue
In electrolytic reduction of alumina _______ is used as a cathode.
Zinc sulphide : Roasting : : zinc carbonate : _______
Explain the following reaction with the balanced equation.
Sodium aluminate reacts with water
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?
Which of the statements about the reaction, \[\ce{ZnO + CO -> Zn + CO2}\] is correct?
