Having more than one atom in its molecule doesn't make
a substance a compound. It's only a compound if it has
atoms of different elements in its molecule.
Both atoms in an Oxygen molecule are the same element ... Oxygen.
<span>Even in space, there is still presence of gravity. The
cause of weightlessness is not how far above the earth the space shuttle is but
rather how fast it is travelling. The shuttle is in free fall causing
weightlessness, but it is travelling fast enough to miss the earth as it falls.
Similarly, the airplane could also provide weightlessness if it went free fall
as well. However, that ends as the plane hits the ground. </span>
