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CBSE Notes for class 9 th


1. Matter in Our Surroundings : Introduction of matter Science class 9th:English Medium NCERT Book Solutions

NCERT Books Subjects for class 9th Hindi Medium

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1. Matter in Our Surroundings


Introduction of matter

1. Matter in Our Surroundings


Matters: Those all objects have mass and occupy space called matters.  

  • Matter is made up of tiny particles.
  • The particles of matter are too much small that we can not imagine. Example - some small particles or crystals of potassium permanganate make a glass of water colourful to add in. one crystal of potassium permanganate, which keep on dividing themselves into smaller and smaller particles. Imagine that how small the particles of matter are ? Which occupy each particles of water in the glass. 

 The characteristics of the particles of matter: 

(i)    Particles of matter have space between them.

(ii)    Particles of matter are continuously moving.

(iii)   Particles of matter attract each other.

(i)    Particles of matter have space between them: How matters like salt, sugar, dettol or potassium permangante intermixes with the particles of water easily? This happens due to enough space between the particles of matter. This is the reason that a diver can able to cut through water in the swimming pool.    

(ii)  Particles of matter are continuously moving : The particles of matter move continuously, so they possess kinetic energy. On increasing temperature the kinetic energy also increases and particle moves faster. 

(iii)  Particles of matter attract each other  There is a force acting between particles of matter. This force keeps particles together.  The strength of this force
of attraction varies from one kind of matter to another. 

Solids have greater attraction force than liquid and gas, while gases have less attraction force. This is the reason that gases spread and solids joins strictly together. 

The states of matters:  

There are three states of matters: 

(i) Solid

(ii) Liquid 

(iii) Gas  

Formation of states of a matter:  

These states of matter arise due to the variation in the characteristics of the particles of matter.

  • Increasing in space amongs particles causes decreasing in attraction force. This less attraction causes changing in states. 

Properties of Solid:

(i)  Solid have a definite shape.

(ii)  Solid have a fixed volume.

(iii)  It cannot be changed its shape.

(iv)  Inter molecular force are strongest in solid.

Properties of Liquid;

(i)   Liquids have no fixed shape.

(ii)  Liquids flow and change shape so they are not rigid.

(iii) They are not compressed.

(iv)  Inter molecular force are less strong in liquids.

Properties of Gas:

(i)  Gases neither have a definite.

(ii)  They can do compressed.

(iii)  Gas can also flow.

(iv) Inter molecular force are large space than solid and liquid.


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