Helium is unreactive.
Helium is pure as it is on the periodic table.
Chemical Change.
Helium is an element which makes it a pure substance.
No, helium is not an example of a heterogeneous substance. Helium is a pure element, which means it is uniform in composition throughout and does not contain different types of molecules or substances mixed together.
Air has many more different substances than helium, which is a single substance. Outside air contains helium.
Helium is pure as it is on the periodic table.
Chemical Change.
chemical change
Helium gas is a pure substance
Helium gas is a pure substance
Chemical Change
Chemical Change.
Chemical change.
Chemical Change.
Chemical change.
Helium is an element (and therefore a pure substance) yes
Chemical change.