Suppose sodium chloride mixes with silica (a hard glassy material that does not dissolve in water) describe a way to remove the sodium chloride

Addition of water to the mixture creates a solution of sodium chloride in water with particles of silica.
 
Filtration of the produced mixture can separate the filtrate (liquid) which is the sodium chloride solution and the solid residue which is the silica in the filter medium. 

Decantation or the pouring of the liquid mixture to leave the solid particles behind can also be a way to remove the sodium chloride solution.

Well to my expert knowledge and my exquisite calculations i think the the negative ion # 412 is the key to sucess

And a) oxygen i believe