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प्रश्न
If copper is kept exposed to damp air for a considerable time, it gets a green coating on its surface. This is due to the formation of:
(a) hydrated copper sulphate
(b) copper oxide
(c) basic copper carbonate
(d) copper nitrate
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उत्तर
(c) basic copper carbonate
Copper reacts slowly with water and carbon dioxide in the atmosphere to form copper carbonate. This gives a green colour coating to its surface.
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संबंधित प्रश्न
Tinning : Tin : : Galvanizing : _________
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| d) Coating of Zinc on iron |
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Sound is produced
| A process of forming a thick oxide of aluminium when aluminium is exposed to air. This coat makes it resistant to corrosion. Resistance can be improved by making a layer of oxide thinker. In this technique, the aluminium article is the anode, and the electrolyte is sulphuric acid. The anode reaction results in the formation of a black-coloured film of aluminium oxide on the anode. By putting appropriate dyes in the electrolytic solution, both coloured surface with the decorative finish is achieved. Kitchen articles like anodised such as pressure cookers, pans and frames of sliding windows are applications of this technique. |
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- Name the technique used to coat the aluminium articles.
