Question

Two groups of students are given $5g$ of iron filings and $3g$ of sulfur powder each. Group X is asked to mix and crush the mixture. Group Y is asked to mix, crush and heat the mixture strongly. The resulting molten mass is then left to cool. Both the groups were asked to separate the components by using a magnet. Which group will be able to do so?
A. Group X
B. Group Y
C. Both X and Y
D. Neither X and Y

Answer 1

Whenever a substance with magnetic property is mixed with impurities such that they produce a heterogeneous mixture, the substance showing magnetic property can be separated using a magnetic field. But when a substance with magnetic property is heated strongly, its magnetic property is lost and it cannot be separated from the impurities using a magnetic field.

Complete answer:
The students in the group X were asked to mix the iron fillings with solid sulfur and crush them to produce a heterogeneous mixture. When this mixture is subjected to a magnetic field, the iron fillings being ferromagnetic in nature get attracted towards the magnetic field immediately and get separated from the sulfur impurities.
The students in group Y were asked to add iron filings with the solid sulfur, crush them, prepare a mixture and to strongly heat them. When they do so, they obtain a molten mixture of iron and sulfur which doesn’t get attracted towards the magnetic field. This is so because there is a loss in the magnetic behavior of the iron fillings when they are subjected to strong heating.

So, the correct answer is Option A.

Note:
Whenever a magnetic substance is strongly heated, the domains present inside it get disoriented and thus, lose the magnetic properties. On strong heating, the atoms which were acting as magnets become randomly oriented in space inside the substance and cannot interact with the external magnetic field.