No, hydrogen gas is not just combined with oxygen. Hydrogen gas (H2) is a pure element, meaning it is made up of only hydrogen atoms.

Here's the breakdown:

* Hydrogen gas (H2): Two hydrogen atoms bonded together to form a molecule. This is the pure, elemental form of hydrogen.

* Water (H2O): This is a compound formed when two hydrogen atoms bond with one oxygen atom. It is not simply hydrogen gas combined with oxygen.

* Hydrogen peroxide (H2O2): This is another compound where hydrogen and oxygen are bonded, but with a different ratio than water.

So, to summarize, hydrogen gas exists independently and does not require the presence of oxygen. It only forms water or other compounds when it chemically reacts with oxygen.