Helium is mono atomic.
Helium is made of atoms.
Helium does not form molecules but exists as individual atoms.
No. Helium consists of individual atoms and does not form molecules or compounds.
The number of helium atoms (not molecules) is 39,7945.10e23.
A molecule of helium is composed of two helium atoms.
Helium is an atom. Heavier elements have molecules.
The pressure that there would be if all the non-helium atoms and molecules were taken away.
Helium atoms are not considered molecules because they exist as individual atoms and do not form covalent bonds with other atoms to create a stable unit like a molecule. In the case of helium, each atom exists independently and does not combine with other atoms to form a molecule.
The pressure that there would be if all the non-helium atoms and molecules were taken away.
So, in a mole of anything, there are 6.022x10^23 molecules or atoms. There are 1000 millimoles in a mole, so 6.022x10^23/1000 is 6.022x10^20 atoms.
Helium atoms are lighter than any atoms/molecules except hydrogen. I don't know what you mean by "the buoyant force".
Helium is a single atom element. It exists as individual atoms and does not form diatomic molecules, molecules, or formula units.