a) The differences in the characteristics of states of matter are given in the following table
| Solid state | Liquid state | Gaseous state | |
| 1. | Definite shape and volume. | No definite shape. Liquids attain the shape of the vessel in which they are kept. | Gases have neither a definite shape nor a definite volume. |
| 2. | Incompressible | Compressible to a small extent. | Highly compressible |
| 3. | There is little space between the particles of a solid. | These particles have a greater space between them. | The space between gas particles is the greatest. |
| 4. | These particles attract each other very strongly. | The force of attraction between liquid particles is less than solid particles. | The force of attraction is least between gaseous particles. |
| 5. | Particles of solid cannot move freely. | These particles move freely. | Gaseous particles are in a continuous, random motion. |
(b)Rigidity can be expressed as the tendency of matter to resist a change in shape.
Compressibility is the ability to be reduced to a lower volume when force is applied.
Fluidity is the ability to flow.
By filling a gas container we mean the attainment of shape of the container by gas.
Shape defines a definite boundary.
Kinetic energy is the energy possessed by a particle due to its motion.
Density is mass per unit volume.