If a gas has two protons in its nucleus, it is helium.

Here's why:

* Protons define the element: The number of protons in an atom's nucleus determines what element it is.

* Helium has two protons: Helium is the second element on the periodic table, meaning it has two protons.

* Gases at room temperature: Helium is a noble gas, which means it exists as a gas at room temperature.