NCERT Textbook: Sorting Materials into Groups | Science & Technology for UPSC CSE PDF Download

 Page 1


Fig. 2.1 Objects around us
2
Sorting Materials into Groups
2.1 OBJECTS AROUND US
We have seen that our food and clothes
have so much variety in them. Not just
food and clothes, there is such a vast
variety of objects everywhere. We see
around us, a chair, a bullock cart, a
cycle, cooking utensils, books, clothes,
toys, water, stones and many other
objects. All these objects have different
shapes, colours and uses (Fig. 2.1).
Look around and identify objects
that are round in shape. Our list may
include a rubber ball, a football and a
glass marble. If we include objects that
are nearly round, our list could also
include objects like apples, oranges, and
an earthen pitcher (gharha).
Let us say, we wish to make a group
of objects that are made of plastics.
Buckets, lunch boxes, toys, water
containers, pipes and many such
objects, may find a place in this group.
There are so many ways to group objects!
In the above examples we have grouped
objects on the basis of their shape or the
materials they are made from.
All objects around us are made of one
or more materials. These materials may
be glass, metal, plastics, wood, cotton,
paper, mud or soil. Can you think of
more examples of materials?
Activity 1
Let us collect as many objects as
possible, from around us. Each of us
could get some everyday objects from
home and we could also collect some
objects from the classroom or from
outside the school. What will we have
in our collection? Chalk, pencil,
notebook, rubber, duster, a hammer,
nail, soap, spoke of a wheel, bat,
matchbox, salt, potato. We can also list
objects that we can think of, but, cannot
bring to the classroom. For example,
wall, trees, doors, tractor, road.
Separate all objects from this
collection that are made from paper or
wood. This way we have divided all objects
Rationalised 2023-24
Page 2


Fig. 2.1 Objects around us
2
Sorting Materials into Groups
2.1 OBJECTS AROUND US
We have seen that our food and clothes
have so much variety in them. Not just
food and clothes, there is such a vast
variety of objects everywhere. We see
around us, a chair, a bullock cart, a
cycle, cooking utensils, books, clothes,
toys, water, stones and many other
objects. All these objects have different
shapes, colours and uses (Fig. 2.1).
Look around and identify objects
that are round in shape. Our list may
include a rubber ball, a football and a
glass marble. If we include objects that
are nearly round, our list could also
include objects like apples, oranges, and
an earthen pitcher (gharha).
Let us say, we wish to make a group
of objects that are made of plastics.
Buckets, lunch boxes, toys, water
containers, pipes and many such
objects, may find a place in this group.
There are so many ways to group objects!
In the above examples we have grouped
objects on the basis of their shape or the
materials they are made from.
All objects around us are made of one
or more materials. These materials may
be glass, metal, plastics, wood, cotton,
paper, mud or soil. Can you think of
more examples of materials?
Activity 1
Let us collect as many objects as
possible, from around us. Each of us
could get some everyday objects from
home and we could also collect some
objects from the classroom or from
outside the school. What will we have
in our collection? Chalk, pencil,
notebook, rubber, duster, a hammer,
nail, soap, spoke of a wheel, bat,
matchbox, salt, potato. We can also list
objects that we can think of, but, cannot
bring to the classroom. For example,
wall, trees, doors, tractor, road.
Separate all objects from this
collection that are made from paper or
wood. This way we have divided all objects
Rationalised 2023-24
12 SCIENCE
Boojho wants to know, whether
we found some materials that
were used for making more than
one type of an object.
into two groups. One group has the
objects that are made from paper or wood
while the other group has the objects
that are not made of these materials.
Similarly, we could separate the things
that are used for preparing food.
Let us be a little more systematic. List
all objects collected, in Table 2.1. Try to
identify the materials that each one is
made of. It would be fun to make this a
large table – collecting information
about as many objects as possible. It
may seem difficult to find out the
materials out of which some of these
objects are made. In such cases, discuss
with your friends, teacher and parents
to identify the materials.
Table 2.1 Objects and the materials
they are made of
s t c e j b O
e r a y e h t s l a i r e t a M
f o e d a m
( e t a l P i l a h t )
s c i t s a l p , s s a l g , l e e t S
) r e h t o y n a (
n e P l a t e m , s c i t s a l P
Activity 2
Table 2.2 lists some common materials.
You can also add more materials in
Column 1 that are known to you. Now,
try and think of everyday objects you
know, that are made mainly of these
materials, and list them in Column 2.
Table 2.2 Different types of objects
that are made from the same
material
l a i r e t a M
f o e d a m s t c e j b O
s l a i r e t a m e s e h t
d o o W
, e l b a t , r i a h C
t r a c k c o l l u b , h g u o l p
. . . , s l e e h w s t i d n a
r e p a P
, s k o o b e t o n , s k o o B
, s y o t , r e p a p s w e n
. . . , s r a d n e l a c
r e h t a e L
s c i t s a l P
n o t t o C
What do we find from these tables?
First, we grouped objects in many
different ways. We then found that
objects around us are made of different
materials. At times, an object is made of
a single material. An object could also
be made of many materials. And then
again, one material could be used for
making many different objects.  What
decides which material should be used
for making any given object? It seems
Rationalised 2023-24
Page 3


Fig. 2.1 Objects around us
2
Sorting Materials into Groups
2.1 OBJECTS AROUND US
We have seen that our food and clothes
have so much variety in them. Not just
food and clothes, there is such a vast
variety of objects everywhere. We see
around us, a chair, a bullock cart, a
cycle, cooking utensils, books, clothes,
toys, water, stones and many other
objects. All these objects have different
shapes, colours and uses (Fig. 2.1).
Look around and identify objects
that are round in shape. Our list may
include a rubber ball, a football and a
glass marble. If we include objects that
are nearly round, our list could also
include objects like apples, oranges, and
an earthen pitcher (gharha).
Let us say, we wish to make a group
of objects that are made of plastics.
Buckets, lunch boxes, toys, water
containers, pipes and many such
objects, may find a place in this group.
There are so many ways to group objects!
In the above examples we have grouped
objects on the basis of their shape or the
materials they are made from.
All objects around us are made of one
or more materials. These materials may
be glass, metal, plastics, wood, cotton,
paper, mud or soil. Can you think of
more examples of materials?
Activity 1
Let us collect as many objects as
possible, from around us. Each of us
could get some everyday objects from
home and we could also collect some
objects from the classroom or from
outside the school. What will we have
in our collection? Chalk, pencil,
notebook, rubber, duster, a hammer,
nail, soap, spoke of a wheel, bat,
matchbox, salt, potato. We can also list
objects that we can think of, but, cannot
bring to the classroom. For example,
wall, trees, doors, tractor, road.
Separate all objects from this
collection that are made from paper or
wood. This way we have divided all objects
Rationalised 2023-24
12 SCIENCE
Boojho wants to know, whether
we found some materials that
were used for making more than
one type of an object.
into two groups. One group has the
objects that are made from paper or wood
while the other group has the objects
that are not made of these materials.
Similarly, we could separate the things
that are used for preparing food.
Let us be a little more systematic. List
all objects collected, in Table 2.1. Try to
identify the materials that each one is
made of. It would be fun to make this a
large table – collecting information
about as many objects as possible. It
may seem difficult to find out the
materials out of which some of these
objects are made. In such cases, discuss
with your friends, teacher and parents
to identify the materials.
Table 2.1 Objects and the materials
they are made of
s t c e j b O
e r a y e h t s l a i r e t a M
f o e d a m
( e t a l P i l a h t )
s c i t s a l p , s s a l g , l e e t S
) r e h t o y n a (
n e P l a t e m , s c i t s a l P
Activity 2
Table 2.2 lists some common materials.
You can also add more materials in
Column 1 that are known to you. Now,
try and think of everyday objects you
know, that are made mainly of these
materials, and list them in Column 2.
Table 2.2 Different types of objects
that are made from the same
material
l a i r e t a M
f o e d a m s t c e j b O
s l a i r e t a m e s e h t
d o o W
, e l b a t , r i a h C
t r a c k c o l l u b , h g u o l p
. . . , s l e e h w s t i d n a
r e p a P
, s k o o b e t o n , s k o o B
, s y o t , r e p a p s w e n
. . . , s r a d n e l a c
r e h t a e L
s c i t s a l P
n o t t o C
What do we find from these tables?
First, we grouped objects in many
different ways. We then found that
objects around us are made of different
materials. At times, an object is made of
a single material. An object could also
be made of many materials. And then
again, one material could be used for
making many different objects.  What
decides which material should be used
for making any given object? It seems
Rationalised 2023-24
13 SORTING MATERIALS INTO GROUPS
Fig. 2.2 Using a cloth tumbler
that we need to know more about
different materials.
2.2 PROPERTIES OF MATERIALS
Have you ever wondered why a tumbler
is not made with a piece of cloth? Keep
in mind that we generally use a tumbler
to keep a liquid. Therefore, would it not
be silly, if we were to make a tumbler
out of cloth (Fig 2.2)! What we need for
a tumbler is glass, plastics, metal or
other such material that will hold water.
Similarly, it would not be wise to use
paper-like materials for cooking vessels.
We see then, that we choose a
material to make an object depending
Appearance
Materials usually look different from
each other. Wood looks very different
from iron. Iron appears different from
copper or aluminium. At the same time,
there may be some similarities between
iron, copper and aluminium that are not
there in wood.
Activity 3
Collect small pieces of different materials –
paper, cardboard, wood, copper wire,
aluminium sheet, chalk. Do any of these
appear shiny? Separate the shiny
materials into a group.
Now, observe as the teacher cuts each
material into two pieces and look at the
freshly cut surface (Fig. 2.3). What do
you notice? Does the freshly cut surface
of some of these materials appear shiny?
Include these objects also in the group
of shiny materials.
Do you notice such a shine or lustre
in the other materials, cut them anyway
as you can? Repeat this in the class with
as many materials as possible and make
a list of those with and without lustre.
Instead of cutting, you can rub the
surface of material with sand paper to
see if it has lustre.
Fig. 2.3 Cutting pieces of materials to see if
they have lustre
on its properties, and the purpose for
which the object is to be used.
So, what are all the properties of
materials that would be important for
their usage? Some properties are
discussed here.
Rationalised 2023-24
Page 4


Fig. 2.1 Objects around us
2
Sorting Materials into Groups
2.1 OBJECTS AROUND US
We have seen that our food and clothes
have so much variety in them. Not just
food and clothes, there is such a vast
variety of objects everywhere. We see
around us, a chair, a bullock cart, a
cycle, cooking utensils, books, clothes,
toys, water, stones and many other
objects. All these objects have different
shapes, colours and uses (Fig. 2.1).
Look around and identify objects
that are round in shape. Our list may
include a rubber ball, a football and a
glass marble. If we include objects that
are nearly round, our list could also
include objects like apples, oranges, and
an earthen pitcher (gharha).
Let us say, we wish to make a group
of objects that are made of plastics.
Buckets, lunch boxes, toys, water
containers, pipes and many such
objects, may find a place in this group.
There are so many ways to group objects!
In the above examples we have grouped
objects on the basis of their shape or the
materials they are made from.
All objects around us are made of one
or more materials. These materials may
be glass, metal, plastics, wood, cotton,
paper, mud or soil. Can you think of
more examples of materials?
Activity 1
Let us collect as many objects as
possible, from around us. Each of us
could get some everyday objects from
home and we could also collect some
objects from the classroom or from
outside the school. What will we have
in our collection? Chalk, pencil,
notebook, rubber, duster, a hammer,
nail, soap, spoke of a wheel, bat,
matchbox, salt, potato. We can also list
objects that we can think of, but, cannot
bring to the classroom. For example,
wall, trees, doors, tractor, road.
Separate all objects from this
collection that are made from paper or
wood. This way we have divided all objects
Rationalised 2023-24
12 SCIENCE
Boojho wants to know, whether
we found some materials that
were used for making more than
one type of an object.
into two groups. One group has the
objects that are made from paper or wood
while the other group has the objects
that are not made of these materials.
Similarly, we could separate the things
that are used for preparing food.
Let us be a little more systematic. List
all objects collected, in Table 2.1. Try to
identify the materials that each one is
made of. It would be fun to make this a
large table – collecting information
about as many objects as possible. It
may seem difficult to find out the
materials out of which some of these
objects are made. In such cases, discuss
with your friends, teacher and parents
to identify the materials.
Table 2.1 Objects and the materials
they are made of
s t c e j b O
e r a y e h t s l a i r e t a M
f o e d a m
( e t a l P i l a h t )
s c i t s a l p , s s a l g , l e e t S
) r e h t o y n a (
n e P l a t e m , s c i t s a l P
Activity 2
Table 2.2 lists some common materials.
You can also add more materials in
Column 1 that are known to you. Now,
try and think of everyday objects you
know, that are made mainly of these
materials, and list them in Column 2.
Table 2.2 Different types of objects
that are made from the same
material
l a i r e t a M
f o e d a m s t c e j b O
s l a i r e t a m e s e h t
d o o W
, e l b a t , r i a h C
t r a c k c o l l u b , h g u o l p
. . . , s l e e h w s t i d n a
r e p a P
, s k o o b e t o n , s k o o B
, s y o t , r e p a p s w e n
. . . , s r a d n e l a c
r e h t a e L
s c i t s a l P
n o t t o C
What do we find from these tables?
First, we grouped objects in many
different ways. We then found that
objects around us are made of different
materials. At times, an object is made of
a single material. An object could also
be made of many materials. And then
again, one material could be used for
making many different objects.  What
decides which material should be used
for making any given object? It seems
Rationalised 2023-24
13 SORTING MATERIALS INTO GROUPS
Fig. 2.2 Using a cloth tumbler
that we need to know more about
different materials.
2.2 PROPERTIES OF MATERIALS
Have you ever wondered why a tumbler
is not made with a piece of cloth? Keep
in mind that we generally use a tumbler
to keep a liquid. Therefore, would it not
be silly, if we were to make a tumbler
out of cloth (Fig 2.2)! What we need for
a tumbler is glass, plastics, metal or
other such material that will hold water.
Similarly, it would not be wise to use
paper-like materials for cooking vessels.
We see then, that we choose a
material to make an object depending
Appearance
Materials usually look different from
each other. Wood looks very different
from iron. Iron appears different from
copper or aluminium. At the same time,
there may be some similarities between
iron, copper and aluminium that are not
there in wood.
Activity 3
Collect small pieces of different materials –
paper, cardboard, wood, copper wire,
aluminium sheet, chalk. Do any of these
appear shiny? Separate the shiny
materials into a group.
Now, observe as the teacher cuts each
material into two pieces and look at the
freshly cut surface (Fig. 2.3). What do
you notice? Does the freshly cut surface
of some of these materials appear shiny?
Include these objects also in the group
of shiny materials.
Do you notice such a shine or lustre
in the other materials, cut them anyway
as you can? Repeat this in the class with
as many materials as possible and make
a list of those with and without lustre.
Instead of cutting, you can rub the
surface of material with sand paper to
see if it has lustre.
Fig. 2.3 Cutting pieces of materials to see if
they have lustre
on its properties, and the purpose for
which the object is to be used.
So, what are all the properties of
materials that would be important for
their usage? Some properties are
discussed here.
Rationalised 2023-24
14 SCIENCE
Fig. 2.4 What disappears, what doesn’t?
Materials that have such lustre are
usually metals. Iron, copper, aluminium
and gold are examples of metals. Some
metals often lose their shine and
appear dull, because of the action of air
and moisture on them. We therefore,
notice the lustre, only on their freshly
cut surface. When you visit an
ironsmith or a workshop, look out for
freshly cut surfaces of metal rods to see
if they have lustre.
Hardness
When you press different materials with
your hands, some of them may be hard
to compress while others can be easily
compressed. Take a metal key and try
to scratch with it, the surface of a piece
of wood, aluminium, a piece of stone, a
nail, candle, chalk, any other material
or object. You can easily scratch some
materials, while some cannot be
scratched so easily. Materials which can
be compressed or scratched easily are
called soft while some other materials
which are difficult to compress are called
hard. For example, cotton or sponge is
soft while iron is hard.
In appearance, materials can have
different properties, like lustre,
hardness, be rough or smooth. Can you
think of other properties that describe
the appearance of a material?
Soluble or Insoluble?
Activity 4
Collect samples of some solid substances
such as sugar, salt, chalk powder, sand
and sawdust. Take five glasses or
beakers. Fill each one of them about two-
thirds with water. Add a small amount
(spoonful) of sugar to the first glass,
salt to the second and similarly, add
small amounts of the other substances
into the other glasses. Stir the contents
of each of them with a spoon. Wait for a
few minutes. Observe what happens to
the substances added to water (Fig. 2.4).
Note your observations as shown
in Table 2.3.
Table 2.3 Mixing different solid
materials in water
e c n a t s b u S
/ r e t a w n i s r a e p p a s i D
r a e p p a s i d t o n s e o d
t l a S
n i y l e t e l p m o c s r a e p p a s i D
r e t a w
r a g u S
d n a S
k l a h C
r e d w o p
t s u d w a S
You will notice that some substances
have completely disappeared or
dissolved in water. We say that these
substances are soluble in water. Other
substances do not mix with water and
do not disappear even after we stir for a
Rationalised 2023-24
Page 5


Fig. 2.1 Objects around us
2
Sorting Materials into Groups
2.1 OBJECTS AROUND US
We have seen that our food and clothes
have so much variety in them. Not just
food and clothes, there is such a vast
variety of objects everywhere. We see
around us, a chair, a bullock cart, a
cycle, cooking utensils, books, clothes,
toys, water, stones and many other
objects. All these objects have different
shapes, colours and uses (Fig. 2.1).
Look around and identify objects
that are round in shape. Our list may
include a rubber ball, a football and a
glass marble. If we include objects that
are nearly round, our list could also
include objects like apples, oranges, and
an earthen pitcher (gharha).
Let us say, we wish to make a group
of objects that are made of plastics.
Buckets, lunch boxes, toys, water
containers, pipes and many such
objects, may find a place in this group.
There are so many ways to group objects!
In the above examples we have grouped
objects on the basis of their shape or the
materials they are made from.
All objects around us are made of one
or more materials. These materials may
be glass, metal, plastics, wood, cotton,
paper, mud or soil. Can you think of
more examples of materials?
Activity 1
Let us collect as many objects as
possible, from around us. Each of us
could get some everyday objects from
home and we could also collect some
objects from the classroom or from
outside the school. What will we have
in our collection? Chalk, pencil,
notebook, rubber, duster, a hammer,
nail, soap, spoke of a wheel, bat,
matchbox, salt, potato. We can also list
objects that we can think of, but, cannot
bring to the classroom. For example,
wall, trees, doors, tractor, road.
Separate all objects from this
collection that are made from paper or
wood. This way we have divided all objects
Rationalised 2023-24
12 SCIENCE
Boojho wants to know, whether
we found some materials that
were used for making more than
one type of an object.
into two groups. One group has the
objects that are made from paper or wood
while the other group has the objects
that are not made of these materials.
Similarly, we could separate the things
that are used for preparing food.
Let us be a little more systematic. List
all objects collected, in Table 2.1. Try to
identify the materials that each one is
made of. It would be fun to make this a
large table – collecting information
about as many objects as possible. It
may seem difficult to find out the
materials out of which some of these
objects are made. In such cases, discuss
with your friends, teacher and parents
to identify the materials.
Table 2.1 Objects and the materials
they are made of
s t c e j b O
e r a y e h t s l a i r e t a M
f o e d a m
( e t a l P i l a h t )
s c i t s a l p , s s a l g , l e e t S
) r e h t o y n a (
n e P l a t e m , s c i t s a l P
Activity 2
Table 2.2 lists some common materials.
You can also add more materials in
Column 1 that are known to you. Now,
try and think of everyday objects you
know, that are made mainly of these
materials, and list them in Column 2.
Table 2.2 Different types of objects
that are made from the same
material
l a i r e t a M
f o e d a m s t c e j b O
s l a i r e t a m e s e h t
d o o W
, e l b a t , r i a h C
t r a c k c o l l u b , h g u o l p
. . . , s l e e h w s t i d n a
r e p a P
, s k o o b e t o n , s k o o B
, s y o t , r e p a p s w e n
. . . , s r a d n e l a c
r e h t a e L
s c i t s a l P
n o t t o C
What do we find from these tables?
First, we grouped objects in many
different ways. We then found that
objects around us are made of different
materials. At times, an object is made of
a single material. An object could also
be made of many materials. And then
again, one material could be used for
making many different objects.  What
decides which material should be used
for making any given object? It seems
Rationalised 2023-24
13 SORTING MATERIALS INTO GROUPS
Fig. 2.2 Using a cloth tumbler
that we need to know more about
different materials.
2.2 PROPERTIES OF MATERIALS
Have you ever wondered why a tumbler
is not made with a piece of cloth? Keep
in mind that we generally use a tumbler
to keep a liquid. Therefore, would it not
be silly, if we were to make a tumbler
out of cloth (Fig 2.2)! What we need for
a tumbler is glass, plastics, metal or
other such material that will hold water.
Similarly, it would not be wise to use
paper-like materials for cooking vessels.
We see then, that we choose a
material to make an object depending
Appearance
Materials usually look different from
each other. Wood looks very different
from iron. Iron appears different from
copper or aluminium. At the same time,
there may be some similarities between
iron, copper and aluminium that are not
there in wood.
Activity 3
Collect small pieces of different materials –
paper, cardboard, wood, copper wire,
aluminium sheet, chalk. Do any of these
appear shiny? Separate the shiny
materials into a group.
Now, observe as the teacher cuts each
material into two pieces and look at the
freshly cut surface (Fig. 2.3). What do
you notice? Does the freshly cut surface
of some of these materials appear shiny?
Include these objects also in the group
of shiny materials.
Do you notice such a shine or lustre
in the other materials, cut them anyway
as you can? Repeat this in the class with
as many materials as possible and make
a list of those with and without lustre.
Instead of cutting, you can rub the
surface of material with sand paper to
see if it has lustre.
Fig. 2.3 Cutting pieces of materials to see if
they have lustre
on its properties, and the purpose for
which the object is to be used.
So, what are all the properties of
materials that would be important for
their usage? Some properties are
discussed here.
Rationalised 2023-24
14 SCIENCE
Fig. 2.4 What disappears, what doesn’t?
Materials that have such lustre are
usually metals. Iron, copper, aluminium
and gold are examples of metals. Some
metals often lose their shine and
appear dull, because of the action of air
and moisture on them. We therefore,
notice the lustre, only on their freshly
cut surface. When you visit an
ironsmith or a workshop, look out for
freshly cut surfaces of metal rods to see
if they have lustre.
Hardness
When you press different materials with
your hands, some of them may be hard
to compress while others can be easily
compressed. Take a metal key and try
to scratch with it, the surface of a piece
of wood, aluminium, a piece of stone, a
nail, candle, chalk, any other material
or object. You can easily scratch some
materials, while some cannot be
scratched so easily. Materials which can
be compressed or scratched easily are
called soft while some other materials
which are difficult to compress are called
hard. For example, cotton or sponge is
soft while iron is hard.
In appearance, materials can have
different properties, like lustre,
hardness, be rough or smooth. Can you
think of other properties that describe
the appearance of a material?
Soluble or Insoluble?
Activity 4
Collect samples of some solid substances
such as sugar, salt, chalk powder, sand
and sawdust. Take five glasses or
beakers. Fill each one of them about two-
thirds with water. Add a small amount
(spoonful) of sugar to the first glass,
salt to the second and similarly, add
small amounts of the other substances
into the other glasses. Stir the contents
of each of them with a spoon. Wait for a
few minutes. Observe what happens to
the substances added to water (Fig. 2.4).
Note your observations as shown
in Table 2.3.
Table 2.3 Mixing different solid
materials in water
e c n a t s b u S
/ r e t a w n i s r a e p p a s i D
r a e p p a s i d t o n s e o d
t l a S
n i y l e t e l p m o c s r a e p p a s i D
r e t a w
r a g u S
d n a S
k l a h C
r e d w o p
t s u d w a S
You will notice that some substances
have completely disappeared or
dissolved in water. We say that these
substances are soluble in water. Other
substances do not mix with water and
do not disappear even after we stir for a
Rationalised 2023-24
15 SORTING MATERIALS INTO GROUPS
Fig. 2.5 (a) Some liquids mix well with
water while (b) some others do not
(a)
(b)
Boojho suggests that we
also check if the liquids that we
used in Activity 5, mix well with
some liquid other than water.
Paheli is curious to know
whether gases also dissolve
in water.
long time. These substances are
insoluble in water.
Water plays an important role in the
functioning of our body because it can
dissolve a large number of substances.
Do liquids also dissolve in water?
Activity 5
Collect samples of vinegar, lemon juice,
mustard oil or coconut oil, kerosene or
any other liquid. Take a glass tumbler.
Fill it up to half with water. Add a few
spoonfuls of one liquid to this and stir
it well. Let it stand for five minutes.
Observe whether the liquid mixes with
water (Fig. 2.5). Repeat the same with
other liquids, as many different liquids
as are available to you. Write your
observations in Table 2.4.
Table 2.4 Solubility of some
common liquids in water
d i u q i L
/ l l e w s e x i M
x i m t o n s e o D
r a g e n i V l l e w s e x i M
e c i u j n o m e L
l i o d r a t s u M
l i o t u n o c o C
e n e s o r e K
Some gases are soluble in water
whereas others are not. Water, usually,
has small quantities of some gases
dissolved in it.  For example, oxygen gas
dissolved in water is very important for
the survival of animals and plants that
live in water.
Objects may float or sink in
water
While doing Activity 4, you might have
noticed that the insoluble solids
separated out from water. You may have
also noticed this with some liquids in
Activity 5.  Some of these materials that
did not mix with water, floated to the
surface of water. Others may have sunk
to the bottom of the tumbler, right? We
notice many examples of objects that
float in water or sink (Fig. 2.6). Dried
leaves fallen on the surface of a pond, a
stone that you throw into this pond, few
We notice that some liquids get
completely mixed with water. Some
others do not mix with water and form
a separate layer when kept aside for
some time.
Rationalised 2023-24