Why no chemical compound of helium is known?

Answer 1

Helium is a noble gas, meaning it has a full outer electron shell. Atoms form compounds by sharing electrons, but helium has a full set, making it an inert gas. The short answer is: It can't form compounds.

Answer 2

No. It"s an inert gas,inert gases do not form compounds. Reactive gases(like Hydrogen ) do, like H-2-O or Hydrogen-Di-Oxide-better known as water.