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.

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.

Explanation: Cast iron is hard but brittle. It is not ductile and does not rust readily. Cast iron cannot be magnetised.

Explanation: Presence of manganese makes cast iron hard and brittle. Therefore, manganese content in cast iron should be kept below 0.75%.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.