Composition of the Atmosphere extended definition. The atmosphere contains many gases, most in small amounts, including some pollutants and greenhouse gases. The most abundant gas in the atmosphere is nitrogen, with oxygen second. Argon, an inert gas, is the third most abundant gas in the atmosphere.
(CNN)Iran has completed the necessary steps in a deal to restrict its nuclear program, meaning international economic sanctions are lifted, officials from the EU and the U.N. nuclear watchdog agency said Saturday. Relations between Iran and the IAEA now enter a new phase.
Who are the Russians Obama just sanctioned, and what do those sanctions mean? On Thursday, President Barack Obama imposed sanctions on Russia as punishment for the cyberattacks on the 2016 presidential election that the U.S. intelligence community unanimously agreed Russia was behind.