Hindi Question

Class 9 Science Chapter 1: Matter in Our Surroundings (Short Notes)

1. Matter

Anything that occupies space and has mass.

Examples: Air, water, plants, animals, objects.

2. Particle Nature of Matter

Matter is made of tiny particles.

Characteristics:

Particles have space between them

Particles are in constant motion

Particles attract each other

3. States of Matter

State

Shape

Volume

Example

Solid

Fixed

Fixed

Ice, Wood

Liquid

Changes to container

Fixed

Water, Oil

Gas

Changes to container

Changes

Oxygen, Steam

4. Change of State

Melting: Solid Liquid

Freezing: Liquid Solid

Evaporation/Boiling: Liquid Gas

Condensation: Gas Liquid

Sublimation: Solid Gas

5. Evaporation

Liquid Gas below boiling point.

Factors increasing evaporation:

Surface area

Temperature

Wind / Air flow

Causes cooling

6. Diffusion

Spreading of particles of one substance into another.

Example: Perfume smell spreading in a room.

Key Points

Matter has mass & volume.

Matter made of tiny particles.

Exists in solid, liquid, gas.

Particles move & attract.

Evaporation Cooling.

Diffusion Particle movement.

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