Question

how can magnesium chloride can be removed from common salt

Answer 1

Small amounts are undoubtedly present since all “table salt” is sodium chloride derived directly or indirectly from sea water which contains significant concentrations of magnesium. However, the concentrations are exceedingly low in most table salt as it is generally, extensively purified during the manufacturing process. On the other hand, sea salt is generally more impure and contains higher concentrations of magnesium chloride.