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प्रश्न
Silver metal does not combine easily with oxygen but silver jewellery tarnishes after some time. How?
उत्तर
Silver metal does not react with oxygen but reacts with hydrogen sulphide gas in the air and forms a thin black layer of silver sulphide (Ag2S) on it. Therefore, silver jewellery or ornaments tarnish due to the formation of a silver sulphide coating on their surfaces.
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संबंधित प्रश्न
Name two metals which are highly resistant to corrosion.
Name the gas produced when calamine ore is calcined.
Manganese metal is extracted from manganese dioxide by a reduction process by making use of:
(a) carbon
(b) hydrogen
(c) electrolysis
(d) aluminium
Zinc blende ore can be converted into zinc oxide by the process of:
(a) roasting
(b) hydrogenation
(c) chlorination
(d) calcination
What is galvanized iron.
Complete the incomplete statement with missing words:
Metals are ______ while non-metals are ______ conductors of heat.
Calcium, copper, lead, aluminium, zinc, chromium, magnesium, iron.
Choose the major metals from the list given above to make the following alloys:
(a) Stainless steel
(b) brass
State the property of the metal being utilized in the following :
| Use of metal | Property |
| Zinc in Galvanization | |
| Aluminium in Thermite welding |
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 ______.
Froth floatation process is generally used to concentrate ______ ores.
