A normal salt is formed by the complete replacement of the hydrogen ions of an acid by a metal ion or ammonium ion. Ammonium salts are also normal salts. Out of the given options, all are salts except for Mg(OH)NO3, which is a complex salt. This is because Mg(OH)2 is a weak base and reacts partially with nitric acid to form a complex salt, which contains the anions of both Mg(OH)2 and HNO3. Thus, the correct answer is Mg(OH)NO3.