Question

The main difference between cast iron and so pig iron is that:
(A) Cast iron is purest form of iron while pig iron is impure
(B) Cast iron has lower carbon content ( $3\%$ ) as compared to pig iron ( $4\%$ ) and is extremely hard and brittle.
(C) Pig iron contains many impurities like $S,P,Si$ and $Mn$ while cast iron does not contain any impurity and can be cast into any shape.
(D) Cast iron is soft and malleable while pig iron is extremely hard and brittle.

Answer 1

Hint : Pig iron obtained by smelting iron ore in a blast furnace. Pig iron is also called crude iron and it is also an intermediate product of the iron industry. But cast iron is obtained by reducing iron ore in a blast furnace. Cast iron has a low melting temperature and is made up of pig iron.

Complete Step By Step Answer:
Pig iron is formed by smelting iron ore in a blast furnace. It has a high content of carbon in it. It has been stated that approximately in pig iron $3.8\%$ to $4.7\%$ higher carbon content present. It also contains some silica and other constituents of dross due to which it is very brittle. Due to this brittleness it is used in limited application. Pig iron contains many impurities like sulphur, phosphorus, silicon and manganese.
But in the case of cast iron, it is formed by reducing the iron ore in a blast furnace and made up of pig iron. It can be directly obtained from the molten pig iron and also by again melting the pig iron along with its treatment with iron, steel, limestone and carbon (coke). It has a lower carbon content approximately of $2\%$ to $4\%$ . It is used widely in applications because of its lower melting temperature.
So, option B is correct.

Note :
Pig iron is more brittle than cast iron and that’s why it is not suitable for making useful articles. Cast iron is very suitable for making useful articles because of its low melting temperature. Cast iron are of four types grey cast iron, white cast iron, malleable cast iron and ductile cast iron.