There are several non-reactive noble gases, but the most common and abundant one is Argon (Ar).

Here's why:

* Noble gases are a group of elements in the periodic table known for their extremely low reactivity. This is because they have a full outer shell of electrons, making them very stable and unlikely to form chemical bonds.

* Argon is the third most abundant gas in the Earth's atmosphere, making it readily available.

Other noble gases include:

* Helium (He)

* Neon (Ne)

* Krypton (Kr)

* Xenon (Xe)

* Radon (Rn)

While all these gases are non-reactive, some like Xenon and Radon can form compounds under specific conditions, making them slightly less "noble" than the rest.