Give reasons: A gas fills completely the vessel in which it is kept.

As its characteristic is high compressibility and low intermolecular forces, a gas fills entirely the vessel where it is stored. Gas particles are far apart with more kinetic energy that allows them to separate from one another. The gas’s particles quickly spread out in all directions when they are placed inside the container, hitting the container’s walls and each other.

Gases do not have fixed shapes or volumes, hence total filling of the vessel. They fill up all the space they find and adopt the form of the receptacle. Gas molecules are very mobile and travel throughout a space randomly until their pressure is equal in every direction, at which point they would fill throughout a vessel.

Moreover, gases are highly compressed and hence they are very compressible thereby making them easy for packing into small volumes. In this way, they can squeeze into whatever space that is available as a gas will always tend to fill its containing container irrespective of its size or shape.