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प्रश्न
Answer the following question.
a) What is meant by corrosion?
b) Write names of any two methods of prevention of corrosion.
c) In which method, metal like copper, aluminium are coated with a thin layer of their oxides by means of electrolysis.
d) Explain this method with diagram.
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उत्तर
a. corrosion: Corrosion is a process where the water or the moisture on the surface of the metal oxidizes with the atmospheric oxygen.
b. Methods of prevention (any two each carry 1/2 mark) 1
1. Galvanizing 2. Anodization 3. Tinning
4. Electroplating 5. Alloying
c. Anodization
d. In this process cupper, aluminum are coated with a thin layer of their oxides by means of electrolysis. For this copper or aluminum article is used as anode. It obstructs the contact of the aluminum or copper with oxygen and water.
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संबंधित प्रश्न
Tinning : Tin : : Galvanizing : _________
Write two methods of preventing the rusting of iron.
Choose the correct answer from the options given below:
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
A. Smelting
B. Ore-dressing
C. Calcination
D. Bessemerisation
What is meant by galvanisation? Why is it done?
Why is an iron grill painted frequently?
Give the constituents of brass.
Name a common metal which is highly resistant to corrosion.
A common metal which is highly resistant to corrosion is ______.
Mention two uses of the following metals and non-metals
Iron
Observe the following picture a write down the chemical reaction with the explanation.
Write three methods of preventing rusting of iron.
What is ‘rusting’?
Answer the following question.
List two properties of alloys.
Give reason.
An iron article should be given a coat of paint
Explain the term – rusting and give a word equation for the formation of rust. If polished iron nails are kept in three separate test tubes, state the contents in each test tube required, to prove the conditions for rusting.
Give reason for the following:
A suspension of rust is basic in nature.
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Find the odd one out and give its explanation.
What is rust?
The process of coating the surface of the metal with a thin layer of zinc is called ______
Give the equation for the formation of rust.
State two conditions necessary for rusting of iron.
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
The diagram shows the reaction between metal and dil. acid.
What is the reason for different behaviour of Mg in test tube B?
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.
Identify the correct statement from the following:
Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?
Galvanisation is a process used to prevent the rusting of which of the following?
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
Explain the following:
Lime water turns milky on passing carbon dioxide gas into it.
Give an example of a chemical reaction for the following situation:
Sound is produced
Explain the chemical reactions in rusting of iron.
| 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.
