They arise by adding base to solutions of molybdic acid. Solid forms of molybdic acid are coordination polymers. The salts of molybdic acid are called molybdates. In acidified aqueous solutions of molybdic acid, the complex MoO(HO) is observed. Molybdenum trioxide dissolves slightly in water to give "molybdic acid". Solutions of ammonium paramolybdate react with acids to form molybdic acid and an ammonium salt. When the powdered mineral is evaporated with HCl, molybdic oxide is formed.