* Homogeneous Mixture: A homogeneous mixture has a uniform composition throughout. This means that the components are evenly distributed and you can't visually distinguish them from one another.

* Helium Gas: Helium is an element, meaning it's made up of only one type of atom. When helium exists as a gas, all the helium atoms are dispersed evenly throughout the space it occupies.

In contrast, a heterogeneous mixture would have visibly different components. For example, sand and water would be a heterogeneous mixture because you could see the separate sand particles and water.