Oxygen (Wikipedia)Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth’s most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas currently constitutes 20.95% of the Earth’s atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth’s crust in the form of oxides.
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Plutarch (Wikipedia)Plutarch (/ˈpluːtɑːrk/; Greek: Πλούταρχος, Ploútarchos; Koinē Greek: [ˈplúːtarkʰos]; c. AD 46 – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for his Parallel Lives, a series of biographies of illustrious Greeks and Romans, and Moralia, a collection of essays and speeches. Upon becoming a Roman citizen, he was possibly named Lucius Mestrius Plutarchus (Λούκιος Μέστριος Πλούταρχος).