Here's why:
* Intermolecular forces: While much weaker than the bonds within molecules, intermolecular forces (like van der Waals forces) do exist between gas molecules. These forces are responsible for things like the condensation of gases into liquids.
* Collisions: Gas particles constantly collide with each other and the walls of their container. These collisions can be considered a form of "pulling" force, as they change the direction and speed of the particles.
However, the statement is partially true in the sense that:
* The attractive forces are very weak: Compared to the forces within liquids and solids, the attractive forces between gas particles are negligible.
* The particles are far apart: Gas molecules are constantly moving and have a large separation between them, further reducing the strength of any attractive forces.
In summary: There are weak attractive forces between gas particles, but they are so weak and the particles are so far apart that these forces are often considered negligible in describing the behavior of gases. This is why we often talk about gas particles as if they were completely independent of each other.