Question

Which is the best process to separate a mixture of sand and iron filings?
A) filtration
B) sedimentation
C) magnetic separation
D) using a compass

Answer 1

Hint
Sand is non-magnetic whereas iron fillings can be used as magnets. So, they can be separated by a method which uses a magnet for separating a mixture. Magnetic separation is the process which uses magnetic force for the extraction of magnetic material from a mixture.

Complete Step by Step Solution
Filtration is the process which is used to separate solids from liquids or gases by using a medium which is termed as filter. The filter allows only liquids or gas to pass through it, solids do not pass through it.
Here, sand and iron filings are neither liquid nor gas. Therefore, this method cannot be used to separate the mixture of sand and iron filings.
Sedimentation is the process which uses gravity to remove suspended solids from water. It is a physical water treatment process. It is the act of depositing sediment. This process cannot be used in a sand and iron filings mixture because none of them is liquid. So, none of them can settle down with each other.
Magnetic separation is the process which uses magnets to attract magnetic materials which separates the components of mixtures. This process is used when one of the components in a mixture is magnetic and the other one is non-magnetic. So, this is the best process to separate a mixture of sand and iron fillings because iron fillings are magnetic and sand is a non-magnetic material. Magnets will attract the iron fillings towards them and sand will not be attracted by which the iron filings and sand will get separated.
Hence, option (C) is correct.

Note
In this process, magnets are situated inside two separator drums which bear liquids. Due to the presence of magnets, the magnetic materials are being drifted by movement of drums. This can create a magnetic concentrate. This technique cannot be used for all but can be used for ferromagnetic and paramagnetic materials.