Gases, Liquids and solids are sometimes contrasted by the fact that liquids and gasses will take on the shape of the container that they are placed in while solids do not.
Both liquids and gases do not have a definite shape, however they will assume the form of the container they are placed in.
its pressure will increase if it is placed in a fixed container, or it will expand if it is free to do so
Because gas has no shape and gases adopt the shape of that container in which gas is placed.
Gases can change volume because they take up the whole space of the container, room, etc. that they are contained in.
Gases change their volume according to the container that they are in. Liquids change shape but not volume, and solids change neither shape nor volume.
Gases can NOT change shape because gases don't have a 'shape', it's the container in which they are held that has a shape)
Gases
Of course. The gas always fills the container it's in, no matter how large or small the volume is.
Basically, have the ability to change shape. (Withot human interferance)They change their shape to fit their container.
-- Gases change their shape and volume to match the container they're in. -- Liquids change their shape but not their volume. -- Solids don't change anything. It doesn't matter if they're in a glass jar, a rubber balloon, or a paper bag. ===== A Gas
No. Only heat, compression, or decompression can change the size of a gas/liquid.