Question

Permanent magnets can be made from:
A) hard steel
B) cobalt steel
C) stainless steel
D) wrought iron

Answer 1

We know that permanent magnets are the substances that are attracted strongly by a magnetic field and can be permanently magnetized as well which is also known as ferromagnetic substance. The ferromagnetic substance from the following options can become permanent magnets.

Complete step by step answer:
We know that the magnetic properties of solids are classified into three types:

1. Diamagnetic material
2. Paramagnetic material
3. Ferromagnetic material
   As we have to find the permanent magnets, let us understand about ferromagnetic substances.
   Ferromagnetic substances are in solid-state and group together into small domains and each domain acts as a tiny magnet. In the external magnetic field, these domains get oriented in the direction of the magnetic field.
   Examples: iron (Fe), nickel (Ni), cobalt (Co), and some alloy of rare earth metal.
   We know that the general chemical formula of hard steel is ${\text{F}}{{\text{e}}_{\text{3}}}{\text{C}}$ and is paramagnetic.
   It is known that stainless steel is the composition of chromium, carbon, and other alloying material. So, it is also a paramagnetic substance.
   Cobalt steel is also known as high-speed steel and is paramagnetic.
   It should be known that the chemical representation of wrought iron is ${\text{F}}{{\text{e}}_{\text{2}}}{\text{Si}}{{\text{O}}_{\text{4}}}$ and as it contains iron in large amounts, it is a ferromagnetic material. Hence, wrought iron can be used to make permanent magnets.

So, the correct answer is Option D .

Note:
In this type of question, we must always search for the ferromagnetic material. As paramagnetic and ferromagnetic both can be attracted by a magnet but only ferromagnetic substances can be permanently magnetized.