sentences:  The most common form is the hexahydrate Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.As well as the anhydrous compound Co(NO3)2, several hydrates of cobalt(II) nitrate exist.These hydrates have the chemical formula Co(NO3)2·"n"H2O, where "n" = 0, 2, 4, 6.