Chemistry Question on Gasses?

Gases and space ....

Does your class occupy your chemistry classroom? Does your class completely fill the room? Didn't think so. There is a lot of empty space in your classroom not occupied by students, but the students still occupy the room. Gases have the additional advantage of moving about the space in three dimensions to give a uniform distribution, with lots of empty space between the molecules, just as there is "empty space" between you and your fellow students.

To summarize: Consider a container with a volume of 1 liter, and some gas molecules occupy the container. The combined volume of the molecules themselves is not 1L (it wouldn't be a gas then), but the molecules are spread out all over the 1L container, and the gas is said to have a volume of 1L.

Because it is space filled or space empty. The gas does not need to push the empty space away. The volume has a number, even if the space exists or not.