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.
Pure substances contain only one type of particles. Even though each molecule in a compound is made of different atoms and each atom is made of protons, neutrons and electrons â¦, a single moleculs is a single particle and since compounds contain only one type of particle (its molecules), it is a pure substance. Is O2 a pure substance ?