What element has the symbol 'Ar'?

The story behind the answer

Argon is correct because the chemical symbol Ar belongs to argon, a noble gas with atomic number 18. It’s colorless, odorless, and extremely unreactive, which is why it’s used to protect metals during welding and to fill light bulbs. In fact, argon makes up about 0.93% of Earth’s atmosphere. The name comes from the Greek “argos,” meaning inactive—perfect for a noble gas.

The other options don’t match Ar: Astatine is At, Arsenic is As, and “Argentium” isn’t an element at all—it’s a silver-based alloy brand. Memory tip: Ar = Argon, and “ar-gone” reminds you it doesn’t react—it’s “gone” from chemical action, just floating in the air.