Question

Why do we fill balloons
with helium gas instead
of oxygen gas?

Answer 1

Answer:

Helium is less dense. Because helium is lighter than air, a helium balloon rises, just as an air bubble rises in more dense water

Explanation:

Also why not. It just is.

Answer 2

Answer:

This is due to the fact that helium has a lower density. A helium balloon rises like an air bubble in more dense water because helium is lighter than air. Another gas lighter than air is hydrogen, which is even lighter than helium.

Explanation: