This set of Building Construction Multiple Choice Questions & Answers focuses on “Ferrous Metals – 2”.
1. Which of the following statements is not true about white cast iron?
a) It has a silvery-white colour
b) White cast iron is quite hard
c) It melts with great difficulty
d) It can be used for delicate castings
Explanation: White cast iron has a silvery-white colour and is quite hard. It melts with great difficulty and cannot be used for delicate castings.
2. In which type of casting, molten metal is poured into moulds which keep on rotating?
a) Centrifugal casting
b) Chilled casting
c) Hollow casting
d) Sand casting
Explanation: There are various types of castings. These are centrifugal casting, chilled casting, hollow casting, sand casting, die casting and vertical sand casting. Molten metal is poured into moulds which keep on rotating in centrifugal casting. Centrifugal casting is usually used to prepare pipes.
3. Which of the following is not a property of cast iron?
a) Cast iron is hard but brittle
b) Cast iron can be magnetised
c) It does not rust readily
d) Cast iron is not ductile
Explanation: Cast iron is hard but brittle. It is not ductile and does not rust readily. Cast iron cannot be magnetised.
4. The manganese content in cast iron should be kept below __________
Explanation: Presence of manganese makes cast iron hard and brittle. Therefore, manganese content in cast iron should be kept below 0.75%.
5. Which variety of cast iron is obtained by melting cast iron with wrought iron scrap?
a) Mottled cast iron
b) Chilled cast iron
c) Malleable cast iron
d) Toughened cast iron
Explanation: Melting cast iron with wrought iron scrap results in the formation of toughened cast iron. Mottled cast iron is an intermediate between white cast iron and grey cast iron.
6. In which type of casting, the outer surface is made hard while the inner surface remains relatively soft?
a) Hollow casting
b) Sand casting
c) Chilled casting
d) Die casting
Explanation: In chilled casting, the outer surface is made hard while the inner surface remains relatively soft. Sudden cooling or chilling makes the outer surface hard. Chilled casting is used for producing wearing surface as in case of tyres.
7. The process of converting pig iron into wrought iron by stirring in the molten state is called as _________
Explanation: There are four operations involved in the manufacturing of wrought iron. These are refining, puddling, shingling and rolling. The process of converting pig iron into wrought iron by stirring in the molten state is called puddling.
8. The process of puddling is carried out in a ________
a) Blast furnace
c) Cupola furnace
d) Reverberatory furnace
Explanation: The process of puddling is carried out in a reverberatory furnace. The metal does not come in contact with the fuel in a reverberatory furnace. This type of furnace is rectangular in shape and built with refractory materials like fire-bricks.
9. The material obtained at the end of the shingling process is called as ________
Explanation: The process of shingling is used to remove the slag contained in the puddle balls. The material obtained at the end of the shingling process is called bloom. The bloom is then passed through grooved rollers to order to obtain flat bars which indicate wrought iron of poor quality.
10. Aston’s process is used to manufacture _________
b) Wrought iron
c) Pig iron
d) Cast iron
Explanation: Aston’s process was developed by James Aston in 1925. It is used to manufacture wrought iron and in a quick and economical way. Aston’s process is fully mechanical.
11. Which of the following is not a property pf wrought iron?
a) Wrought iron is ductile and malleable
b) It fuses easily
c) The specific gravity of wrought iron is about 7.8
d) Wrought iron can be easily forged and welded
Explanation: Wrought iron is ductile and malleable. Wrought iron fuses with difficulty but it can be easily forged and welded. The specific gravity of wrought iron is about 7.8.
12. Corrosion of ferrous metals is known as ___________
d) Coal Tarring
Explanation: Corrosion of ferrous metals is known as rusting. Rusting of cast iron is less and rusting of wrought iron is medium while that of steel is found to be much more. Enamelling, coal tarring and galvanising are some of the methods used to prevent corrosion.
13. Which metal is used in the galvanisation of iron in order to prevent it from rusting?
Explanation: Zinc is used in the galvanisation of iron in order to prevent it from rusting. The layer of zinc is more reactive than iron, and hence it cuts the contact of iron with air or moisture and protects it from rusting.
14. Which chemical is used in the method of parkerizing, adopted to prevent corrosion?
Explanation: In the method of parkerizing, adopted to prevent corrosion, the article to be treated for corrosion is immersed in a hot water bath of a chemical called Pareo. Insoluble phosphates are created on the surface of the article which keeps away the moisture.
15. Dust of pure _________ is used to cover the article to be treated for corrosion in the method of sherardising.
Explanation: Dust of pure zinc is used to cover the article to be treated for corrosion in the method of sherardising. It is then heated to a suitable temperature in an airtight steel box which results in the melting of zinc. It then combines with the metal and creates a protective layer on its surface and thus prevents it from rusting.
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