You may improve this article, discuss the issue on the talk page, or create a new article, as appropriate. (January 2015) The history of economic thought deals with different thinkers and theories in the subject that became political economy and economics, from the ancient world to the present day. It encompasses many disparate schools of economic thought.
A pure substance is a substance that cannot be separated by physical means. eg. filtration, evaporation, distillation or chromatography. Examples of pure substances include water, gold, glucose, carbon dioxide, oxygen and hydrogen. A pure substance is made up of one type of particle. The particle that makes up water is H 2 O. The particle that makes up carbon dioxide is CO 2.
Elements and compounds are pure substances because they both have fixed compositions or uniformed compositions. 3 people found this useful. Edit. Share to: 1  Chemistry: Common Hazard Symbols and Their Meanings You don't need to be a chemist to decipher hazard symbols on products or bottles of chemical agents.here are two ways to think about this. Chemically, the element is a pure substance (each atom has the same number of protons). Nuclear speaking, the element may be represente â¦ d by a number of different isotopes (different number of neutrons).