A compound is a chemical substance that forms when two or more different elements combine in a fixed ratio. Water (H2O), for example, is a compound that is made up of two hydrogen atoms for every one oxygen atom. Sodium chloride (NaCl) is a compound made up of one sodium atom for every chlorine atom.
Hudson, Iowa. Hudson is a city in Black Hawk County, Iowa, United States. The population was 2,282 at the 2010 census. The rural community of Hudson has grown in recent years and is included as a part of the Waterloo-Cedar Falls Metropolitan Statistical Area. Contents.
McGregor, Iowa. McGregor is a city in Clayton County, Iowa, United States. The population was 871 at the 2010 census. McGregor is located on the Mississippi River across from Prairie du Chien, Wisconsin. Pike's Peak State Park is located just south of the city. Just to the north of McGregor is the city of Marquette.