EXERCISE
BE
PROMPT
A.
Fill in the blanks
1. Mass is the measure of quantity
of matter contained in a substance
2. Resistance
is a force that tends to oppose motion.
3. Liquids are free
flowing because the molecules are loosely packed.
4. In gases the intermolecular forces between the
molecules are very weak.
5. The space between the molecules of a substance is
called intermolecular space.
6. Sublime
is the gaseous state of solid.
B. State whether the following
statements are TRUE or FALSE
1. Matter is composed of extremely small
particles. (TRUE)
2. A molecule has an independent existence and also
exhibits all the properties of matter. (TRUE)
3. Liquids have strong force of attraction. (FALSE)
4. Solids have less density than liquids. (FALSE)
5. The particles in gases move rapidly in all
directions. (TRUE)
6. Brownian motion is caused by the collision of
molecules. (TRUE)
C. Choose the correct option.
1. Which of the following statement is not true for
mass?
(a) It is the quantity of matter. (b) It is constant everywhere
(c) It is
the amount of force of gravity acting on the mass
2. _________ refers to the intermingling of
particles of different substances
on their own.
(a) Combining (b)
Mixing (c) Refining (d)
Diffusion
3. Which of the following have closely packed
particles?
(a) Solids (b) Liquids (c)
Gases (d) All of these
4. Which of the following diffuse quickly?
(a) Solids (b)
Liquids (c) Gases (d) All of
these
5. Which of the following can be compressed to some
extent?
(a) Solids (b) Liquids (c) Gases (d)
All of these
6. What is the process of conversion of a liquid in to
a solid called?
(a) Freezing (b) Condensation (c)
Sublimation
(d) Evaporation
D. Match the columns.
Column A Column B
1. Conversion of a
solid in to liquid (a)
Vaporization
2. Conversion of a
gas in to liquid (b)
Chemical change
3. Conversion of a
solid in to gas (c)
Melting
4. Conversion of a
liquid in to vapour (d)
Sublimation
5. Burning of a
candle (e)
Condensation
Ans. 1 – (c), 2 – (e), 3 – (d), 4 – (a), 5 – (b).
SHORT
AND PRECISE
A.
Give reasons for the following statements.
1.
The three states of matter are different from each other.
The three
states of matter are different from each other due to the
intermolecular
space, cohesive forces and random motion of particles.
2.
Solids are firm, compact and almost incompressible.
In solids
molecules are closely packed together and the intermolecular
forces are the
strongest. Therefore, solids are firm, compact and almost
incompressible.
3. Ice kept
at room temperature for 5-10 minutes changes in to water.
When ice is
kept at room temperature it gains heat energy from its
surroundings.
On gaining heat energy the molecules start moving faster.
Later the
intermolecular forces between the molecules decreases and
the
intermolecular space increases. At this stage ice changes in to
water.
4. Water
kept in a freezer of a refrigerator changes in to ice.
When water is
kept in a freezer it losses heat. Due to loss of heat the
energy of
molecules decreases. Their movement slows down and they
come closer to
each other. At some time a stage reaches when the
movement of
molecules becomes so slow that water changes in to ice.
5. Gas
changes in to liquid state on cooling.
When gas is
cooled its molecules loss energy. On loosing energy their
movement slows
down. After some time a stage reached when the
movement of
molecules becomes so slow that the gas changes in to
liquid.
6. Gases can
be compressed easily.
The molecules
in a gas are loosely packed and the intermolecular space
are very
large. Due to this reason gases can be compressed easily.
7. Water
changes in to water vapour on heating.
When water is
heated, its molecules get heat energy and start moving
away from each
other. As the temperature increases a stage reached
when the
molecules gain so much energy, that they leave the surface
and changes in
to steam (gas).
8.
Naphthalene balls are placed in cupboards between woolen clothes to
keep insects
away.
Naphthalene
balls are placed in cupboards between woolen clothes to
keep insects
away because naphthalene sublimes in to vapour, which
drive out the
insects.
B.
Answer in short.
1. Define
matter give examples.
Matter is anything that occupies space and has mass.
All substances
whether living or non-living are made up of matter.
Example: Air, water,
paper, wood, metal, cloth, trees, animals, etc.
2. What are solids? How are molecules
arranged in solids?
Matter which have a definite shape, mass and
volume are known as solids. Solids are
incompressible and have high density. The
molecules in a solid are closely packed and the
intermolecular forces
are the strongest.
3. How are molecules arranged in gases?
In gases the molecules are loosely
packed. The intermolecular space
between the molecules is very large
as the intermolecular forces are
weak.
4. Explain, why solids are hard and
difficult to compress.
In solids the molecules are closely packed and the
intermolecular
forces are the strongest. Because of this the solids
are hard and difficult
to compress.
5. Define freezing and freezing point.
The process of conversion of a liquid in to solid is
called freezing or
solidification. The constant temperature at which a
liquid changes in to
solid is called its freezing point.
6. What is vaporization? Name its two types.
The process by which a liquid changes in to its
gaseous or vapour state
is known as vaporization. Vaporization is of two
types, evaporation and
boiling.
7. What is condensation? Define condensation point.
When a gas is cooled it condenses to form a liquid.
This process is called
condensation or liquefaction. The constant temperature
at which a gas
changes in to a liquid is called the condensation point.
8. What happens on heating a
solid?
When a solid
is heated the molecules in it gain the heat energy and start
moving faster.
A stage is reached when the energy gained by the molecules
overcome the
inter-molecular forces between the molecules. Then the
molecules break free and begin to move even faster. At
this stage the solid
changes to
liquid.
AT
LENGTH
A.
Differentiate between the following.
1.
Mass and weight
Mass
|
Weight
|
It is the
quantity of matter.
|
It is the
amount of force of gravity acting on the mass.
|
It is
constant everywhere.
|
It varies
from place to place
|
It cannot be
zero
|
It can be
zero if there is no gravity as in outer space.
|
2.
Solids, Liquids and gases
Solids
|
Liquids
|
Gases
|
The
molecules are closely packed.
|
The
molecules are less closely packed
|
The
molecules are further apart.
|
The
intermolecular force of attraction is very strong.
|
The
intermolecular force of attraction is not so strong.
|
The
intermolecular force of attraction is weak.
|
Solids have
definite shape and volume
|
Liquids have
a definite volume but no definite shape.
|
Gases
neither have definite shape nor definite volume.
|
Solids do
not flow
|
Liquids are
free flowing
|
Gases flow
in all directions.
|
Solids have
high density and almost incompressible
|
Liquids have
low density and can be compressed to some extent
|
Gases have
very low density and can be compressed easily.
|
3.
Brownian motion and diffusion
Brownian
motion
|
Diffusion
|
The zig zag
motion of small particles caused by the collision of molecules is called
Brownian motion.
|
The
phenomenon of intermingling of substances by the natural movement of their
particles is called diffusion.
|
4.
Boiling and evaporation
Boiling
|
Evaporation
|
Boiling
occurs at a given temperature called boiling point of the liquid.
|
Evaporation
takes place at all temperatures lower than the boiling point of the liquid.
|
It is a
rapid process.
|
It is a slow
process.
|
It occurs
throughout the liquid.
|
It takes
place only from the surface of the liquid.
|
There is no
cooling effect during boiling.
|
There is a
cooling effect during evaporation.
|
It occurs
only when the liquid is heated.
|
It takes
place on its own.
|
5.
Condensation and deposition
Condensation
|
Deposition
|
The process
in which the gas is cooled to form liquid is known as condensation.
|
A direct
change of state from gas to solid is called deposition.
|
B.
Answer in details.
1.
With the help of an activity show that matter has mass.
Aim: To show
that matter has mass
Materials
required: A can, some water, a spring
balance, a
thread.
Procedure: i)
Suspend a spring balance from a hook.
read zero.
ii) Tie an
empty can with a strong cotton thread and
suspend the can
from the hook
of the spring balance.
iii) Note the
reading of the pointer.
iv) Now fill
the can with some water.
Observation:
The spring balance with the can having water shows more
reading.
Conclusion: This shows that the
matter has mass.
2.
Write a note on states of matter.
There are
three states of matter, solid, liquid and gas. The states of
matter depends
upon the intermolecular forces and intermolecular
space. The
three states of matter are different due to the
different
arrangements of molecules in them. Matter in the solid state
have molecules
closely packed and the intermolecular force is the
strongest.
Matter in the liquid state has molecules less closely packed
and the
intermolecular force is lesser than those of solids. Matter in the
gaseous state
has molecules far apart from each other and the inter –
molecular
force is very weak.
3.
Give an activity to show that solids have definite volume.
Aim: To observe that the solids
have a definite
volume.
Materials
required: A
small bowl, 2 large bowls, a
tumbler, a
thread, a paper weight.
Procedure
1
·
Take
a glass bowl and a glass tumbler and
fill
them with equal quantity of water.
·
Place
both of them in bigger bowls.
·
Take
a paper weight and tie it with a long thread.
·
Suspend
the paper weight in to the glass bowl.
Observation 1: It will be observed that when the
paper weight is suspended in to the glass bowl, some water flows out of it in
to the larger bowl.
Procedure 2:
·
Measure
the volume of water collected in the larger bowl using a measuring cylinder.
Let it be x ml.
·
Now
remove the paper weight from the glass bowl and suspend it in to the glass
tumbler.
Observation 2: It will be observed that when the
paper weight is suspended in to the glass tumbler, some water flows out of it
into the larger bowl.
·
Measure
the volume of water collected in the bowl using a measuring cylinder. Let it be
y ml.
·
Compare
the two volumes x ml and y ml
Conclusion: It will be observed that
the volume of water collected in both the cases same. This shows that solids
have a definite volume.
4. With the help of an activity show that liquids have definite volume butnot fixed shape.
Aim: To observe that liquids have a definite volume but no fixed shape.
Materials required: A measuring cylinder, a cup, a glass bowl, some Water.
Procedure:
·
Take
100 ml water using a measuring cylinder.
·
Pour
the water in a glass and observe its shape.
·
Then
transfer the water to a cup and observe its shape.
·
At
last transfer the water to a bowl and observe its shape.
·
Measure
the volume of water using a measuring cylinder.
Observation: It will be observed that each time
the water takes the shape of the container (i.e, glass, cup and bowl). But
every time the volume of water remains the same (i.e, 100ml)
Conclusion:
This shows
that have a definite volume but no fixed shape.
It takes the
shape of the container.
**************************************************************
5. Explain the existence of three states
of matter.
At ordinary
temperature and pressure matter exists in three states, based
on the
arrangement of molecules it them. These three states of matter are
solid, liquid
and gas. Matter in the solid state have molecules closely
packed and the
intermolecular force is the strongest. Matter in the liquid
state has
molecules less closely packed and the intermolecular force is
lesser than
those of solids. Matter in the gaseous state has molecules far
apart from
each other and the intermolecular force is very weak.
6.
State the factors responsible for the difference in properties of states of
Matter.
The factors
which are responsible for the difference in properties of
s tates of
matter are: -
·
Intermolecular
space.
·
Intermolecular
force of attraction.
·
Random
motion of particles.
7.
What do you understand by change in states of matter? How does this
happen?
Matter can be
changed from one state to other by supplying or removing
heat energy.
On heating the molecules of matter move rapidly. Due to their continuous movement they change from one state to another.
All the three
states of matter are inter-convertible.
When the solid
is heated the molecules get heat energy and start moving
faster. A
stage reached when the solid changes to liquid. Similarly on
heating a
liquid the molecules get heat energy and start moving even
faster. At
this stage the liquid converts in to gas. On the other hand when
the gas is
cooled the molecules loose their heat energy and get closer. At
this stage the
gas converts in to liquid. When the liquid is further cooled
the molecules loose their heat energy further and get more closer.
This stage of matter is known as solid.
8. How does water on heating change in to vapour state?
A chemical change can be caused by heating a substance. For
the molecules loose their heat energy further and get more closer.
This stage of matter is known as solid.
8. How does water on heating change in to vapour state?
When water is
heated, its molecules get heat energy and start moving
away from each
other. As temperature increases, a stage reached when
the molecules
gain so much energy that they leave the surface and
change in to
water vapour. This process of change of a liquid to its vapour
state is known
as boiling.
9.
Explain the thermal expansion in solids, liquids and gases.
All the three
states of matter, (solids, liquids and gases) expand on
heating. On
heating a solid the molecules get energy and force each
other further
apart. This results in the expansion of a solid. The same thing
happens in
case of the molecules in liquid or gas on heating. The
molecules
force each other further apart causing expansion. On heating
a liquid
expands more than a solid and gas expands enormously on
heating.
10.
How the chemical change caused due to heating? Explain with the
help
of an example.
A chemical change is the permanent change in any substance. A
new
substance is formed when a chemical change occurs. Property
of this
newly formed substance is entirely different from the
original substance. A chemical change can be caused by heating a substance. For
example, when we burn a piece of paper it changes in to ash,
which
is a new substance. The property of ash is different from the
property of
paper. We can not change ash in to paper. This shows that
burning of
paper causes a chemical change. **************************************************************
Extra Questions and Answers
A. Objective
Questions
1. Fill in
the blanks
a) Space is the void between the particles of matter.
b) Everything in the universe is composed of matter.
c) Matter exists in
both natural and man-made states.
d) Mass is the measure of quantity of matter
contained in a substance.
e) Matter has mass and occupies space.
f) Molecule
is the smallest particle of matter that has independent
existence and
exhibits all properties of matter.
g) The molecules
attract each other with a force called intermolecular
force.
h) Plasma is an ionized gas which consists of
both negatively charged
particles and
positively charged particles.
i) The matter in the sun exists in the form of plasma.
j) The inter molecular force of attraction decreases as the inter-
molecular space between the molecules
increases.
k) Diffusion refers to the intermingling of
particles of different substances
on their own.
l) Liquids
and gases are fluid because they can
flow and their shape is
not fixed.
m) Cohesive forces are
the intermolecular forces that exist between
molecules of the
same substance.
n) Some liquids such as
mercury also possess strong cohesive
forces.
o) Robert brown discovered
the random movement of particles.
p) The process of
conversion of a solid in to its liquid state is called
melting.
q) The process of
conversion of liquid in to solid is called freezing.
r) The process by which liquid changes in to gas
is called vaporization.
s) During evaporation
a liquid gains heat energy from its surroundings.
t) The process of change of liquid
to its gaseous state on heating is
called boiling.
u) A direct change of
state from gas to solid is called deposition.
v) The gaseous state of
a solid is called sublime
w) The solid obtained
on cooling the vapour is called sublimate.
x) Gas expand enormously when heated.
y) All the three states
of matter expands on heating.
z) A chemical change involves the formation of new
substance.
e) Give some examples of compressed gases.
******************************************************************************
2. Answer in one word:
a) The phenomenon of
intermingling of substance by the natural
movement of
their particles – Diffusion.
b) The constant
temperature at which liquid changes in to gas –
Boiling point.
c) The constant
temperature at which liquid changes in to solid –
Freezing point.
d) The constant
temperature at which liquid changes in to vapour
state – Boiling point.
e) The constant
temperature at which gas changes in to liquid –
Condensation point
f) The solid obtained on cooing the vapour – Sublimate
g) The gaseous state of
solid – Sublime
h) A permanent change
in which new substance is formed –
Chemical change
i) The forth state of matter – Plasma
j) The amount of force of gravity acting on the
mass – Weight
h) The amount of matter
contained per unit volume – Density.
i) Some liquids like oil and water do not mix
together and are called –
Immiscible liquid.
j) Liquids like milk and water which mix with
each other are called –
Miscible liquids.
K) The zig-zag movement
of small particles in a suspended medium –
Brownian motion.
m) The process in which
gas changes to liquid – Condensation.
3. Correct the statement.
a) An atom has an
independent existence.
A molecule has an independent existence.
b) Matter
exists in four states.
Matter exists in three states.
c) Gases
possess high density.
Solids possess high density.
d) Liquids are
free flowing because the molecules are tightly packed.
Liquids
are free flowing because the molecules are loosely packed.
e) The
constant temperature at which gas changes in to liquid is called
melting point.
The constant temperature at which gas
changes in to liquid is called
condensation point.
f) Sublime is
the solid obtained on cooling the liquid.
Sublime is the gaseous state of solid.
g) The particles in solid move rapidly in all directions.
The particles in gas move rapidly in all
directions.
h) Solids can be compressed
easily.
Gases can be compressed easily.
i) Liquids diffuse very rapidly.
Gases
diffuse very rapidly.
k) Mass of a matter varies
from place to place.
Mass of a matter is constant everywhere.
4. Match the columns:
(Ans.) 1-(e), 2-(c), 3-(d),
4-(a), 5-(b)
4. Match the columns:
Column
A Column
B
1. Mass (a) Highly compressible
2. Resistance (b) Gaseous state of a solid
3. Atom (c) Force opposing motion
4. Gases (d) Smallest possible unit of matter
5. Sublime (e) Measure of quantity of matter
B. Short Questions
1. Define the following:
a) Solidification:
When water is kept in a
freezer, it losses heat. Due to loss of heat, the
energy
of molecules decreases and they come closer to each other.
A
stage comes when the movement of molecules becomes so slow
that
water changes to ice. This process of conversion of liquid in to solid
is
called freezing or solidification.
b) Evaporation:
A
liquid gets heat energy from its surroundings and changes in to
vapour
state. This process is called evaporation. Evaporation occurs
at all temperatures lower than the boiling
temperature of a liquid.
It is a slow process. Cooling is caused during
evaporation.
c) Boiling point:
The
constant temperature at which liquid changes in to gas is called
boiling
point.
d)
Deposition:
The process in which a gas is
directly changes in to solid form is known
as deposition.
e)
Chemical change:
A chemical change is a change in which new substances are formed.
It is a permanent change. After a
chemical change the properties of
the newly formed substance is
entirely different from those of the
original substance. A chemical
change can be caused by heating a
substance.
f) Matter:
Matter is anything that occupies space and has mass. Matter is
composed of extremely small
particles and it exists in both natural and
man made state. Everything in
this universe is composed of matter.
g) Atom:
Matter is made up of very tiny particles known as atom. An atom
usually does not exists
independently. It is the smallest possible unit of
matter. Atoms combine to form
molecules.
h)
Element:
An element is made up of same types of atoms. Some examples of
elements are Oxygen (O2),
Hydrogen (H) etc.
i)
Compound:
Compounds are made up of two different types of atoms. Examples of
compounds are water (H2O),
carbon dioxide (CO2)
j)
Sublimation:
On heating some solids like iodine, camphor, naphthalene and
ammonium chloride directly changes
in to gaseous state without
changing in to a liquid state. This
process in which a solid directly
converts in to gaseous state is
called sublimation.
C. Long Questions
a) Define boiling.
When water is heated, its molecules get heat
energy and start moving
away
from each other. As temperature increases a stage is reached
when
the molecules get enough energy to leave the surface and
changes
in to vapour or steam. This process of change of a liquid in to
gas
on heating is called boiling.
b) Write the properties of a solid.
The
properties of solid are
·
Solids
have a definite shape, mass and volume.
· Solids
are in-compressible.
·
Solids
have high density.
·
Solids
do not diffuse.
c) Write the properties of liquid.
The
properties of liquid are
·
Liquids
have no fixed shape, but a definite volume. They take the
shape of the container they are
stored in.
·
Liquids
can not be compressed.
·
Liquids
have a tendency to flow. They are free flowing because the molecules are
loosely packed.
·
Liquids
have less density than solids.
·
Liquids
can diffuse.
d) Write the properties of gas.
The
properties of gas are
·
Gases
neither have a definite shape nor a definite volume.
·
Gases
have maximum capacity to flow.
·
Gases
are highly compressible.
·
Gases
have very low density.
·
Gasses
diffuse very rapidly.
e) Give some examples of compressed gases.
Some examples of compressed gases are.
i) LPG (liquefied petroleum gas) that we use in our houses for cooking.
ii) Oxygen supplied to hospitals, mountaineers and sea divers in
cylinders.
iii) CNG (compact natural gas) used as fuel in
vehicles.
f) Give an activity to
show that matter occupies space.
Aim: To show that matter occupies space.
Materials required: Some water, a tumbler, some sand, a spoon.
Procedure:
i) Take a glass tumbler and fill it
with some water.
ii) Mark the level of water on the
outer surface of the glass tumbler.
iii) Now add four spoon of sand in to
the glass tumbler.
iv) Again mark the level of water in
the glass tumbler.
v) Compare the two marks.
Observation: It will be observed that the sand
settles down and the level
of water increases.
Conclusion: The sand added in to the glass
tumbler occupies some space. Therefore, the level of water increases. This
shows that matter occupies
space.
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