Q2. Answer the following.

a) Tabulate the differences in the characteristics of matter.

b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

###### Answer :

(a) The difference in the characteristics of the three states of matter.

 Characteristics Solid Liquid Gas Shape Fixed shape No Fixed shape No Fixed shape Volume Fixed volume Fixed volume No Fixed volume Intermolecular force Maximum Less than solids Very less Intermolecular space Very less More than solids maximum Rigidity/Fluidity Rigid/cannot flow Can flow/not rigid Can flow/not rigid Compressibility negligible compressible Highly compressible

(b) (i) Rigidity: It is the property of a substance to retain its shape whe an external force is acted upon it.

(ii) Compressibility: When the intermolecular space between the particles of a matter reduces due an external force, this property is known as compressibility. Gases and liqiuds are compressible but not solids.

(iii) Fluidity: The tendency of a particle to flow is called fluidity. Gases and liqiuds can flow but not solids.

(iv) Filling of a gas container: Gases have particles which vibrate in all direction randomly and takes the shape of container in which it is stored.

(v) Shape: It is the definite structure of an object within an external boundary. Solids have definite shape (due to high intermolecular forces) and liquids and gases takes the shape of container in which they are stored.

(vi) Kinetic energy: Energy which is possessed by particles due to their motion is reffered to as kinetic energy. Order of max. kinetic energy in different states are: Solids < Liquids < Gases.

(vi) Density: It is defines as the mass per unit volume of a substance, i.e.,   $$d =$$ $$M \over V$$      where, ‘d’ is the density, ‘M’ is the mass and ‘V’ is the volume of the substance.