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

Answer: (i) Rigidity: It is the propensity of a substance to continue to remain in its shape when treated with an external force.

(ii) Compressibility: It is the attribute of the particles to contract its intermolecular space when exposed to an external force thereby escalating its density.

(iii) Fluidity: It is the ability of a substance to flow or move about freely.

(iv) Filling the gas container: The particles in a container take its shape as they randomly vibrate in all possible directions.

(v) Shape: It is the definite structure of an object within an external boundary

(vi) Kinetic energy: Motion allows particles to possess energy which is referred to as kinetic energy. The increasing order of kinetic energy possessed by various states of matter are:

Solids < Liquids < Gases

Mathematically, it can be expressed as K.E = 1/2 mv2, where ‘m’ is the mass and ‘v’ is the velocity of the particle.

(vii) Density: It is the mass of a unit volume of a substance. It is expressed as:

d = M/V, where ‘d’ is the density, ‘M’ is the mass and ‘V’ is the volume of the substance