Question

What types of substances don't have definite volume?

Answer 1

Both solids and liquids have definite volumes. What does that leave?

Explanation:

Gases have indefinite volume; they may be compressed or expanded. Given a container, that may be very large, an introduced gas will fill the container uniformly whatever the size. Gaseous mixtures also will thus fill a container (or an atmosphere) uniformly.

`"Dalton's Law of partial pressures"` states that in a gaseous mixture, the pressure exerted by a component gas is the same as the pressure it would exert if it ALONE occupied the container.

See this old answer for further details.