Argon
Ar is Argon. Argon is a colourless and odourless gas that is present in a very small part of the atmosphere.
Here are some baffling mysteries about the universe no one has figured out yet.
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He
Hint, this is the second element on the periodic table.
Helium
Did you guess that He was Helium? Helium is the second most abundant element in the universe.