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 are made up of only one type of atom. There are elements which are naturally occurring and those produced artificially in the laboratory. The elements Aluminum, Calcium, Helium, iron, Nitrogen, Potassium, Argon, Carbon, Gold, Hydrogen, Neon, Oxygen, Silver are some of the examples for pure substances.ntroduction to list of pure substances: A pure substance is that which consists of only one component with definite physical and chemical properties and with a definite composition. A pure substance may be either an element or a compound.