Sea is the greatest source of halogens. Comment.
Sea water contains chlorides, bromides and iodides of sodium, potassium, magnesium and calcium , but mainly sodium chloride (2.5% by mass). Dried up sea beds contain sodium chloride and carnallite KCl. MgCl2. 6H2O. Certain seaweeds contain upto 0.5% of iodine as sodium iodide and chile saltetres (NaNO3) contains upto 0.2% of sodium iodate. Thus, sea is the greatest source of halogens.