Answer:
c) Soft iron should be used as the core of an electromagnet rather than steel because soft iron loses its magnetism when there is no electric current flowing through it, whereas steel does not lose its magnetism when there is no electric current flowing through it.
d) It is important to note that the strength of an electromagnet is proportional to the number of turns made in its coil, the length of space between its poles, and the amount of current running through it.