Page 15 - Understanding NCERT Science 09
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1.3 States of Matter the force is removed. If excessive force is
applied, it breaks.
Observe different types of matter around you. • The shape of each individual sugar or
What are its different states? We can see that salt crystal remains fixed, whether we
matter around us exists in three different take it in our hand, put it in a plate or in
states– solid, liquid and gas. These states of a jar.
matter arise due to the variation in the • A sponge has minute holes, in which
characteristics of the particles of matter. air is trapped, when we press it, the air
Now, let us study about the properties of is expelled out and we are able to
these three states of matter in detail. compress it.
1.3.1 THE SOLID STATE 1.3.2 THE LIQUID STATE
Activity _____________ 1.9 Activity _____________1.10
• Collect the following articles — a pen, • Collect the following:
a book, a needle and a piece of wooden (a) water, cooking oil, milk, juice, a
stick. cold drink.
• Sketch the shape of the above articles (b) containers of different shapes. Put
in your notebook by moving a pencil a 50 mL mark on these containers
around them. using a measuring cylinder from
• Do all these have a definite shape, the laboratory.
distinct boundaries and a fixed volume? • What will happen if these liquids are
spilt on the floor?
• What happens if they are hammered,
pulled or dropped? • Measure 50 mL of any one liquid and
transfer it into different containers one
• Are these capable of diffusing into each
by one. Does the volume remain the
other?
same?
• Try compressing them by applying
• Does the shape of the liquid remain the
force. Are you able to compress them?
same ?
All the above are examples of solids. We • When you pour the liquid from one
can observe that all these have a definite container into another, does it flow
shape, distinct boundaries and fixed volumes, easily?
that is, have negligible compressibility. Solids We observe that liquids have no fixed
have a tendency to maintain their shape when shape but have a fixed volume. They take up
subjected to outside force. Solids may break the shape of the container in which they are
under force but it is difficult to change their kept. Liquids flow and change shape, so they
shape, so they are rigid. are not rigid but can be called fluid.
Refer to activities 1.4 and 1.5 where we
Consider the following:
saw that solids and liquids can diffuse into
(a) What about a rubber band, can it liquids. The gases from the atmosphere
change its shape on stretching? Is it diffuse and dissolve in water. These gases,
a solid? especially oxygen and carbon dioxide, are
(b) What about sugar and salt? When essential for the survival of aquatic animals
kept in different jars these take the and plants.
shape of the jar. Are they solid? All living creatures need to breathe for
(c) What about a sponge? It is a solid survival. The aquatic animals can breathe
yet we are able to compress it. Why? under water due to the presence of dissolved
All the above are solids as: oxygen in water. Thus, we may conclude that
• A rubber band changes shape under solids, liquids and gases can diffuse into
force and regains the same shape when liquids. The rate of diffusion of liquids is
4 SCIENCE
Rationalised 2023-24
