Question

Bull Type)
(a) How do you describe so many substances
around us in one word?
(h) Are invisible substances like gases or air
also constitute matter?
(c) What about certain feelings like love, hate,
security, smell?
(d) Why?​

Answer 1

Answer:

Explanation:

 Physical nature of matter: Matter is a substance

which occupies mass and space. Its presence may

or may not be felt. Air is matter but smell, hate,

love or security which are felt are not matter. Further matter is particulate, i.e., it is not continuous

but made up of tiny particles.

 Characteristics of matter: Particles of matter have

space between them. They are constantly moving.

These interact and diffuse into one another. Diffusion decreases from gases to liquids to solids.

 States of matter: The particles of matter attract

each other. This attraction is called intermolecular

force of attraction. Depending on the magnitude

of intermolecular forces, a matter may exist as

solid, liquid or a gas. The gap between particles

increases from solid to liquid to gas.

A solid has a definite shape and a definite volume and

is rigid, has boundary, has negligible compressibility.

A liquid has a definite volume but no definite shape,

has boundary but not rigid.

A gas has no shape, no boundary and no fixed volume.

Change of state of matter: A solid on heating

changes into a liquid which changes into gas on

further heating. On cooling, reverse process takes

place. On heating, kinetic energy of particles

increases which is responsible for change of state

of matter.

 Latent heat: At the melting point, temperature

becomes constant, though heat is supplied, till

whole of solid melts. Similarly during heating of

liquid, at the boiling point, temperature remains

constant. These are respectively called latent heat

of fusion and vaporisation.

 Sublimation: In some cases, matter changes directly from solid state to gaseous state and vice

versa without changing into liquid state.

 Effect of pressure: On increasing pressure,

particles of matter come closer and they move

apart on reducing pressure at a given temperature.

Thus increasing pressure liquifies a gas. Similarly

solid becomes liquid at lower pressures.

 Evaporation: Particles of matter are always

moving and at different speeds. (We measure

average speed). In case of liquid, when particles

having higher kinetic energy reach the surface,

break away by the forces of attraction of other

particles and get converted into vapours. This

phenomenon gives rise to cooling of water in

earthenwares. The rate of evaporation increases

with temperature, surface area, speed of wind and

decreases with humidity

Answer 2

Explanation:

how do you describe so many substances around us in one word ?