Chapter 1

NCERT
Class 9
Science
Solutions

Question:

(a) Tabulate the differences in the characteristics of states of matter.

(b) Comment upon the following:

Rigidity, Compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

(a)

Solid Liquid Gas
(I) They have both fixed
volume and shape.
They have fixed volume but not
fixed shape.
They don’t have fixed volume
and shape
(II) They cannot be
compressed
They can be partially compressed They can be compressed very
much
(III) They do not flow They flow They flow
(IV)They have high density They have density less than solid They have very less density

(b) Rigidity: The intermolecular force of solid substances are very strong by which they strongly bind with each other, This is why they can neither be compressed nor separate from each other. This property of solid is called rigidity.

Compressibility: Only gases have the property of compressibility. Maximum gas can be easily filled in small vessels. This property of gases is called compressibility.

Fluidity: The substance which can flow easily is called fluid and this property of substance to flow is called fluidity.

Filling a gas container: To keep a large volume of gas in a less volume vessel by compressing is called filling a gas container.

Shape: Space occupied by any object is called its shape.

Kinetic energy: The energy generated by motion of any object is called its Kinetic energy.

K.E. = 1/2 mv2

Density: The mass per unit volume of any object is called it’s density.

Density = Mass / Volume