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प्रश्न
Give reasons:
Platinum, gold and silver are used to make jewellery.
Give a reason for the following:
Silver, gold and platinum are used to make jewellery.
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उत्तर
- Gold, silver, and platinum are the least reactive metals. They do not react with air, water, acids, alkalis, or other gases in the environment, so their shine lasts for years.
- Due to their bright lustre and resistance to corrosion, gold, silver, and platinum are used to make jewellery.
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संबंधित प्रश्न
Tinning : Tin : : Galvanizing : _________
Name the metal which is used for galvanising iron.
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Explain why, through aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
What is corrosion?
In stainless steel alloy, iron metal is mixed with:
(a) Cu and Cr
(b) Cr and Ni
(c) Cr and Sn
(d) Cu and Ni
Name the metal which is a constituent of blood pigment?
Name the metal which is a constituent of plant pigment?
What is corrosion? What are necessary conditions for corrosion?
Identify the process shown in the diagram and explain it in short
Give reason.
An iron article should be given a coat of paint
Give reason for the following:
A suspension of rust is basic in nature.
Corrosion of silver causes a black layer of _______.
Rusting of iron : Fe2O3 : : corrosion of copper : ______
Draw a neat labelled diagram.
Electroplating
What is rust?
What is rust?
Explain the following:
Lime water turns milky on passing carbon dioxide gas into it.
Explain the following:
Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate.
| 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. |
- Name the anode and electrolyte used in this technique.
- How can we make aluminium articles made resistant to corrosion?
- Name the technique used to coat the aluminium articles.
