Question

Pure form of Iron is known as
A. Cast iron
B. Steel
C. Wrought iron
D. Iron only

Answer 1

Hint: The different forms of iron have a different amount of carbon content. The form having minimum carbon content is the pure form of the iron.

Complete step by step answer:
Iron is extracted from its ore in the form of different alloys such as pig, wrought, cast and steel. The iron separated at a different level of the iron extraction process has a different composition. All the alloys of iron mainly differ based on carbon content.

The pig iron contains almost $3 - 4\, \% $ carbon and some impurities such as sulphur.
The cast iron contains almost $2 - 3\, \% $ carbon.
The wrought iron contains the lowest, almost $0.08\,\% $ carbon.
Steel contains almost $98 - 99\, \% $ iron and the rest is carbon.

The cast iron contains $2 - 3\,\% $ carbon so the option (A) is incorrect.

The steel contains carbon and some other impurities such as sulphur, manganese so, the option (B) is incorrect.

The form having the lowest carbon content is the purest form that is wrought iron. Therefore, option (C) Wrought iron is correct.

Iron includes all alloys of iron pure as well as impure so, option (D) cannot be correct.

Additional information: Ore of the iron are magnetite, hematite, limonite, and siderite. The ore having a high amount of iron are magnetite and hematite, so these are commercially important. Ore is a naturally occurring heterogeneous mixture generally containing one metal in excess. Alloy is a homogeneous mixture containing at least one metal and extracted from ore by a particular extraction method.

Note:
The purest form of the iron is the form that has the highest amount of iron and the lowest amount of carbon. As the number of processes and steps increases in the extraction method, the impurities remove and purity increase. The pig iron is known as the cheapest form of iron that contains the highest amount of impurities.