Yes, in chemistry a pure substance means either an element or a compound. Thus, hydrogen, oxygen, sodium, iron, copper etc. are pure substances; and so are compounds such as water, sugar, ammonia, sodium chloride, methane, ethanol etc. A compound is composed of two or more elements combined in a fixed ratio by mass. Like an element, a compound also has a distinct chemical identity. A mixture is not a pure substance as it is a collection of two or more elements/compounds in varying ratio. Air, sea water, gasoline, vegetable oils, steel etc. are mixtures.
Hudson (CDP), Massachusetts. Hudson is a census-designated place (CDP) in the town of Hudson in Middlesex County, Massachusetts, United States. The population was 14,907 at the 2010 census.
According to the most recent demographics data available from the Census Bureau released in December of 2017, Figure 1 Hudson County indicates it has 668,526 population which is the 5th in population out of 10 total in the area.