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प्रश्न
Write three methods of preventing rusting of iron.
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उत्तर
Three methods of preventing rusting of iron:
A. Galvanizing: It is a process of giving a thin coating of zinc on iron or steel to protect them from corrosion, E.g. shiny iron nails. pins etc.
B. Rusting of iron can be prevented by coating it with paint, oil, grease or varnish.
C. Tinning: In this process thin layer of tin is coated over iron objects.
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संबंधित प्रश्न
Which metals do not corrode easily?
Name the metal which is used for galvanising iron.
State two conditions for the rusting of iron.
Explain why, though aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
What is corrosion?
What is the corrosion of iron known as?
Explain why, when a copper object remains in damp air for a considerable time, a green coating is formed on its surface. What is this process known as?
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 ______.
What is corrosion? What are necessary conditions for corrosion?
Observe the following picture a write down the chemical reaction with the explanation.
Find the odd man out:
To prevent corrosion of iron and steel _______ method is used.
Find the odd one out and give its explanation.
Write the name.
Method used to present corrosion of copper.
Write scientific reason.
On exposure to air, silver articles turn blackish after some time.
Draw a neat labelled diagram.
Electrolysis
The table shown below gives information about four substances: A, B, C and D.
| SUBSTANCE | MELTING POINT (K) | ELECTRICAL CONDUCTIVITY | |
| SOLID | LIQUID/ AQUEOUS | ||
| A | 295 | Good | Good |
| B | 1210 | Poor | Good |
| C | 1890 | Poor | Good |
| D | 1160 | Poor | Poor |
Identify Ionic compounds from the above given substances.
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.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
