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प्रश्न
Why is an iron grill painted frequently?
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उत्तर
To prevent rusting of iron substances, they are painted frequently. Iron is a reactive metal and it starts corroding in the presence of air (oxygen) and water (or moisture). Iron reacts with oxygen present in the moist air and forms a brown flaky iron oxide (or rust) layer on its surface. This is called rusting. This rusting causes huge damage to iron substances by making them weak. Therefore, an iron grill is painted frequently to prevent corrosion.
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संबंधित प्रश्न
Give two examples of alloys with their chemical composition.
Which metals do not corrode easily?
Explain why Iron sheets are coated with zinc during galvanization.
The chemical reaction involved in the corrosion of iron metal is that of:
(a) oxidation as well as displacement
(b) reduction as well as combination
(c) oxidation as well as combination
(d) reduction as well as displacement
What is the corrosion of iron known as?
What are the constituents of stainless steel?
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
Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
Identify the process shown in the diagram and explain it in short
State whether the statement given below is true or false. If false write the correct statement.
Either oxygen or moisture is essential for rusting.
Pressure cooker : Anodizing : : Silver plated spoons : _______
Write scientific reason.
Coins are made from metals and alloys.
Draw a neat labelled diagram.
Electroplating
Observe the following diagram and write answers.
- Name the method.
- Explain the method.
- Give two examples of this method.
What is rust?
Copper objects lose their shine and form green coating of ____________.
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:
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
