a neutral substance
41United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …
42atom — /at euhm/, n. 1. Physics. a. the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical… …
43spectroscopy — spectroscopist /spek tros keuh pist/, n. /spek tros keuh pee, spek treuh skoh pee/, n. the science that deals with the use of the spectroscope and with spectrum analysis. [1865 70; SPECTRO + SCOPY] * * * Branch of analysis devoted to identifying… …
44Metaphysics — This article is about the branch of philosophy dealing with theories of existence and knowledge. For the work of Aristotle, see Metaphysics (Aristotle). For the occult field, see Metaphysics (supernatural). Philosophy …
45digestive system, human — Introduction the system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract (alimentary canal), or the series of structures and organs through which food and liquids pass… …
46Europe, history of — Introduction history of European peoples and cultures from prehistoric times to the present. Europe is a more ambiguous term than most geographic expressions. Its etymology is doubtful, as is the physical extent of the area it designates.… …
47List of fictional elements, materials, isotopes and atomic particles — This list contains chemical elements, materials, isotopes or (sub)atomic particle that exist primarily in works of fiction (usually fantasy or science fiction). No actual periodic elements end in ite , though many minerals have names with this… …
48PH — is the measure of the acidity or alkalinity of a solution. It is formally a measure of the activity of dissolved hydrogen ions (H+), but for very dilute solutions, the molarity (molar concentration) of H+ may be used as a substitute with little… …
49Glossary of fuel cell terms — The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but …
50Christianity — /kris chee an i tee/, n., pl. Christianities. 1. the Christian religion, including the Catholic, Protestant, and Eastern Orthodox churches. 2. Christian beliefs or practices; Christian quality or character: Christianity mixed with pagan elements; …
