A) A chemical reaction that involves the formation of and insoluble product (precipitate, solid) is called Precipitation. The reactants ate soluble, but the product formed would be insoluble and seperates out as a solid. B) Precipitation is a process for selectively seperating hydrophobic materials from hydrophilic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry. Where it was one of the great enabling technologies of the 20 th century. It has been described as "the single most important operation used for the recovery and upgrading of sulfide ores" C) Precipitation respectively involve the recovery and purification of metals using electrode position of metals at the cathode, and either metal dissolution or a competing oxidation reaction at the anode. D) Precipitation is a process for selectively seperating hydrophobic materials from hydrophlic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry. Where it was one of the great enabling technologies of the 20 th century. It has been described as "the single most important operation used for recovery and upgrading of sulfide ores." E) Precipitation process is a redox reaction used in the batteries