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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
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
In one method of rust prevention, the iron is not coated with anything. Which is this method?
What is corrosion?
What are the special properties of stainless steel?
Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
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.
What are the adverse effects of corrosion?
Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
Give reason.
Copper and brass utensils should be tinned.
Give a reason why rust turns moist red litmus blue.
State whether the statement given below is true or false. If false write the correct statement.
Either oxygen or moisture is essential for rusting.
Rusting of iron : Fe2O3 : : corrosion of copper : ______
Draw a neat labelled diagram.
Electroplating
The process of coating the surface of the metal with a thin layer of zinc is called ______
Amalgam is an alloy 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.
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?
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
