The element that would move with the fastest average speed while in thermal equilibrium in the atmosphere is hydrogen.
<h3>What is hydrogen?</h3>
Hydrogen (H) is a colorless, tasteless, odorless, flammable and gaseous substance that is the simplest member of the family of chemical elements. Hydrogen, with the atomic number 1, is the lightest chemical element in the universe. It is also the most abundant element in the universe.
A hydrogen atom has a nucleus consisting of a proton bearing a unit of positive electrical charge; an electron, bearing a unit of negative electrical charge, is also associated with this nucleus.
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