Std. 9th - Science and Technology, English Medium,...
Transcript of Std. 9th - Science and Technology, English Medium,...
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STD. IX Science
and Technology
Written as per the revised syllabus prescribed by the Maharashtra State Board of Secondary and Higher Secondary Education, Pune.
Printed at: Repro India Ltd., Mumbai
Sixth Edition: March 2016
10054_10512_JUP
P.O. No. 15191
Salient Features
• Exhaustive coverage of entire syllabus in “Question-answer format”.
• Covers answers to all Textual Questions, In-text Questions and Activities.
• Includes MCQs based on practicals and Questions based on diagrams /
flow-charts.
• Includes Higher Order Thinking Skills (HOTS). • Includes Solved and Practice Problems for better preparation.
• Neat and labelled diagrams.
• Includes Memory Maps at the end of each chapter to facilitate quick
revision.
Preface We bring to you “Std. IX: Science and Technology” a complete and thorough guide extensively drafted to boost the students’ confidence. This book has been written as per the latest syllabus and covers answers not only to the textual questions but also for the In-text questions and activities. All the important definitions, laws and formulae are also duly incorporated. In addition to this, solved and practice problems are included which not only aim at covering the topic but also make students ready to face the competition. The topic-wise classified “question and answer” format of this book helps students in easy comprehension. Numerical problems included at the end of respective topics help the student to understand the technique of solving them efficiently. Moreover, neat and labelled diagrams, wherever necessary, are given so as to provide sound understanding of the concept. It also includes MCQs based on Practicals (as per the latest paper pattern). Higher Order Thinking Skills (HOTS) questions have been added for the student to gain insight on the various levels of theory-based questions. Every chapter ends with a Memory Map to facilitate quick revision of the lesson learnt.
There is always room for improvement and hence we welcome all suggestions and regret any errors that may have occurred in the making of this book. Please write to us on : [email protected] A book affects eternity; one can never tell where its influence stops.
Best of luck to all the aspirants! From Publisher
No. Chapter Name Page No.
1 World of Matter 1
2 Understanding Matter 15
3 Inside the Atom 28
4 Counting Matter 39
5 Cell: The unit of Life 51
6 Life: Simple and Complex 71
7 Life Around You 98
8 Highway to Health 122
9 Quality Food, Quality Life 146
10 Moving Objects 169
11 The Laws of Motion 185
12 The Pull of the Earth 199
13 Why Bodies Float 212
14 Energy : The Driving Force 225
15 The Music of Sound 242
16 Bonding with Ecosystems 258
17 Solid Waste – Ecofriendly Management
271
Contents
Note: Textual Questions are represented by * mark. Intext Questions are represented by # mark. Section A : Chapter No. 3, 4, 10, 11, 12, 13, 14, 15, 16 Section B : Chapter No. 1, 2, 5, 6, 7, 8, 9, 17
1
Chapter 01: World of Matter
1.1 Properties of matter 1. ______ is a physical quantity which expresses
the amount of matter in a body. (A) Mass (B) Density (C) Volume (D) Temperature 2. The space inside a container that is occupied
by matter is its ______. (A) density (B) mass (C) volume (D) shape 3. ______ is the ratio of mass of a substance to
its volume. (A) Viscosity (B) Fluidity (C) Density (D) Elasticity 1.2 States of matter 4. Solids are usually ______ since their particles
are closely packed together. (A) soft (B) spongy (C) compressible (D) hard 5. A rubber band is a good example of solids
being ______. (A) elastic (B) rigid (C) hard (D) strong 6. Liquids do not have a definite ______. (A) volume (B) shape (C) density (D) mass 1.3 Change of state 7. The phase or state of matter can change when
the ______ of the substance changes. (A) temperature (B) mass (C) weight (D) amount 8. ______ is the fifth state of matter. (A) Liquid (B) Bose-Einstein condensate (C) Gas (D) Plasma 9. The ______ of a liquid is the temperature at
which the liquid gets converted into solid. (A) freezing point (B) melting point (C) boiling point (D) evaporation 10. Melting point of glucose is ______. (A) 100 oC (B) 218.4 oC (C) 150 oC (D) 110 oC
11. Water freezes at ______. (A) 101 oF (B) 32 oF (C) 212 oF (D) 202 oF 1.4 Evaporation, cooling by evaporation,
condensation 12. ______ is the process by which liquid gets
converted into gaseous form at any temperature below its boiling point.
(A) Melting (B) Evaporation (C) Freezing (D) Condensation 13. ______ is the formation of liquid drops from
vapour. (A) Evaporation (B) Condensation (C) Boiling (D) Melting 1.5 Sublimation 14. ______ is a process in which solids go directly
into gaseous state without going through the liquid state.
(A) Evaporation (B) Sublimation (C) Boiling (D) Melting 15. ______ is not a sublimatory substance. (A) Iodine (B) Camphor (C) Ammonium chloride (D) Solid ice 1.6 Absorption of heat 16. The outer side of the container of a solar
cooker is painted ______. (A) blue (B) black (C) white (D) red 17. Cricketers playing a test match wear ______
clothes. (A) blue (B) black (C) white (D) red 18. Traditionally umbrellas are ______ in colour. (A) yellow (B) blue (C) white (D) black
World of Matter01 Rewrite the following statements by selecting the correct option
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Std. IX: Science and Technology
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Experiment 1 : To measure the temperature of hot water as it cools and plot a time-temperature graph 1. When a sample of hot water is cooled slowly
to room temperature, the temperature of the sample _______.
(A) increases (B) decreases (C) remains constant (D) either increases or decreases 2. Under which condition will the hot water cool
faster? (A) When it is kept in open space. (B) When it is kept in a thermos flask. (C) When it is kept inside a refrigerator. (D) When it is kept near a burning stove. 3. Four students plot the time – temperature
graphs of hot water as it cools to room temperature. These graphs are given below:
The correct graph is plotted by _______. (A) Student A (B) Student B (C) Student C (D) Student D Experiment 2 : To separate the components of a given mixture of sand, common salt and ammonium chloride (or camphor) 1. The components of the mixture of common
salt and ammonium chloride can be separated by _______.
(A) sublimation (B) filtration (C) cooling (D) crystallization
2. When a mixture of sand, camphor and common salt is heated, camphor _______.
(A) condenses to a liquid (B) melts to a liquid (C) sublimates to a gas (D) remains as it is 3. On adding water to a mixture of sand and
common salt, _______. (A) both sand and common salt dissolve in
water (B) sand remains as it is but common salt
dissolves in water (C) common salt remains as it is but sand
dissolves in water (D) both sand and common salt remain
insoluble in water Experiment 3 : To determine the melting point of ice and the boiling point of water 1. The melting point of ice is _______. (A) 10 C (B) 0 C (C) 32 C (D) 100 C 2. The boiling point of water is ______. (A) 32 C (B) 80 C (C) 100 C (D) 150 C 3. The process by which a solid gets converted
into a liquid at a fixed temperature is called _______.
(A) melting (B) evaporation (C) boiling (D) condensation 4. The following phase changes will be observed
when ice is heated till it gets converted to steam:
A Heat Liquid Heat C The phases A and C are _______ respectively. (A) solid and liquid (B) solid and gas (C) gas and solid (D) liquid and gas 1.1 Properties of matter 1. The ______ of an object gives an indication of
the amount of matter that an object contains. 2. ______ is made up of very tiny particles. 3. Matter has ______ and ______. 1.2 States of matter *4. We usually find matter in ______, ______ and
______ forms. 5. The particles in a solid are bound to each other by a ______.
Fill in the Blanks
Practical Based Multiple Choice Questions
O Time
Tem
pera
ture
Student D
O Time
Tem
pera
ture
Student A
Tem
pera
ture
O Time Student C
O Time
Tem
pera
ture
Student B
3
Chapter 01: World of Matter
Answer the following questions in one sentence each
6. Particles of a solid cannot move much. This is one of the ______ characteristics of solids.
7. Liquefied Petroleum Gas (LPG) cylinders are
used at home and ______ cylinders are used in vehicles.
8. ______ spread out to fill the container. 9. ______ can be easily compressed. 1.3 Change of state *10. On heating, solids get converted to ______
and ______ get converted to gases. 11. ______ describes a physical state of matter. 12. Our body temperature is measured in a unit
called the ______. 1.4 Evaporation, cooling by evaporation,
condensation 13. ______ is the process which creates clouds. 1.5 Sublimation *14. ______ and ______ are sublimatory
substances. 15. Out of sand and iodine, iodine is a ______
substance. 1.6 Absorption of heat 16. ______ enters the object and warms it. Answers 1. mass 2. Matter 3. volume, mass 4. solid, liquid, gaseous 5. force 6. physical 7. Compressed Natural Gas (CNG) 8. Gases 9. Gases 10. liquids, liquids 11. Phase 12. Fahrenheit 13. Condensation 14. Camphor, naphthalene balls 15. sublimatory 16. Heat 1.0 Introduction 1. What is matter? Ans: Anything that occupies space, has mass and
can be perceived through our senses is called matter.
1.1 Properties of matter 2. What is density? Ans: Density is the ratio of mass to volume.
Density (d) =Mass(m)
Volume(v)
3. What happens when kerosene and water are mixed?
Ans: When kerosene and water are mixed, kerosene forms the upper layer as it has less density than water.
*4. Why does ice float on water? Ans: Ice floats on water because density of ice is
less than density of water. 1.2 States of matter 5. What is a solid? Ans: A substance which has a definite shape and
volume is called a solid. Eg. Book, wall, rock, etc. 6. What is crystal lattice? Ans: The atoms in a crystal are arranged in a
regular repeating pattern called as crystal lattice.
7. What is rigidity? Ans: The property of the solids to maintain their
volume and shape when subjected to external forces is known as rigidity.
8. What is a liquid? Ans: A substance which does not have a definite
shape, but has a definite volume is called a liquid.
Eg. Water, Mercury, etc. 9. What is a gas? Ans: A substance which has neither a definite shape
nor a definite volume is called a gas. 1.3 Change of state 10. Give the different states of matter. Ans: There are five different states of matter: solid,
liquid, gas, plasma and Bose-Einstein condensate.
*11. How are gases liquefied? Ans: Gases are liquefied by lowering their
temperature below a particular temperature and by applying high pressure.
12. What is melting point of a solid? Ans: The temperature at which a solid gets
converted into a liquid is called the melting point of the solid.
13. What is melting? Ans: The process by which a solid gets converted
into the liquid state at a fixed temperature is called melting.
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Std. IX: Science and Technology
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14. What is freezing point of a liquid? Ans: The temperature at which a liquid gets
converted into a solid is called the freezing point of the liquid.
15. Give the formula for conversion of
temperature in degree Fahrenheit to degree Celsius.
Ans: The formula for conversion of temperature in degree Fahrenheit to degree Celsius is:
(F 32) 5
9= C.
1.4 Evaporation, cooling by evaporation,
condensation 16. What is evaporation? Ans: Evaporation is the process by which a liquid
gets converted into the gaseous form at any temperature below its boiling point.
17. State the factors which affect rate of
evaporation of liquid. Ans: Surface area, temperature, humidity, wind
speed, etc. are the factors which affect the rate of evaporation of liquid.
18. What is condensation? Ans: Condensation is the formation of liquid drops
from vapour. 19. Which process creates clouds and is
essential for snow and rain formation? Ans: Condensation is the process which creates
clouds and is essential for snow and rain formation.
1.5 Sublimation 20. What is sublimation? Ans: The process in which a solid gets directly
converted into the gaseous state without going through the liquid state is called sublimation.
1.1 Properties of matter 1. State the characteristics of matter. Ans: Characteristics of matter: i. Matter is made up of very tiny particles. These particles have space between
them. ii. The particles of matter attract each
other. iii. Matter occupies space. iv. Matter has volume and mass.
1.2 States of matter 2. State the characteristics of solids. Ans: Characteristics of solids: i. Solids have a definite shape and
volume. ii. Solids are almost incompressible, i.e.,
their volume and shape do not change even if an external force is applied.
iii. Most solids are rigid, while some are elastic.
iv. The particles in a solid are closely packed and the forces holding these particles together are quite strong.
*3. Why do solids have a definite shape? Ans: Solids have a definite shape because: i. The particles of solids are very close to
each other. ii. The forces holding these particles are
strong. 4. What is elasticity of solids? Ans: Elasticity of solids: When an external force is applied to a solid,
its shape changes and when this external force is removed, the solid regains its original shape.
This property of solids is known as elasticity. Eg. Rubber band, spring, etc. 5. State the characteristics of liquids. Ans: Characteristics of liquids: i. Liquids have a definite volume. ii. Liquids do not have a definite shape.
They take the shape of the container in which they are kept.
iii. Liquids cannot be compressed easily. iv. Liquids flow and have the property of
viscosity. 6. State the characteristics of gases. Ans: Characteristics of gases: i. Gases flow. ii. Gases spread everywhere in the
available space. iii. Gases do not have definite shape and
volume. iv. Gases can be easily compressed. #7. It is easier to walk through air than
through water. Why is it so? Ans: i. Air is in gaseous state and water is in
liquid state. ii. In air, the particles are so far apart that the
resistance offered by air to the motion of a body through it is negligible.
iii. In water, the particles are closer than in air and the resistance offered by them is more than that of air.
Hence, it is easier to walk through air than through water.
Answer the following questions
5
Chapter 01: World of Matter
1.3 Change of state *8. What is the physical state of water at: i. 257 °C ii. 100 °C iii. 0 °C Ans: i. At 257 °C, water is in gaseous state. ii. At 100 C, water co-exists in liquid and
gaseous state. iii. At 0 C, water co-exists in the solid and
liquid state. 1.4 Evaporation, cooling by evaporation,
condensation 9. Why does a desert cooler cools better on a
hot dry day? Ans: i. On a hot dry day, the temperature is
higher. Thus, there is more dryness in the surrounding air (i.e., relative humidity of the air is low).
ii. At a high temperature, rate of evaporation is more. Thus, a desert cooler produces more cooling which results in large fall in the temperature of its surrounding air.
Hence, a desert cooler cools better on a hot dry day.
#10. Why do we wear cotton clothes in summer? Ans: i. The temperature of the surrounding
becomes very high in summer due to which we feel hot and sweat.
ii. Cotton clothes absorb sweat easily. iii. Heat is taken from the body for
evaporation of sweat. iv. Thus, due to evaporation of sweat, body
temperature remains constant. Hence, we wear cotton clothes in summer. #11. We find dewdrops, especially in the early
morning on the leaves. Why? Ans: i. A given volume of air can hold a certain
maximum amount of water vapour at a particular temperature.
ii. As the temperature falls, the capacity of air to hold water vapour becomes less.
iii. During cold nights, the temperature of air may fall to dew point or below the dew point.
iv. Thus, excess of water vapour in air condenses to form drops which falls on the leaves at night.
Hence, we find dewdrops, especially in the early morning on the leaves.
1.6 Absorption of heat #12. Why do we paint the outer side of the
container of a solar cooker with black paint?
Ans: i. In a solar cooker, the food is cooked due to the heat energy obtained from the sun.
ii. A black surface absorbs about 98% of the incident heat radiation that falls on it.
iii. Due to this, the temperature of the solar cooker increases and the food is cooked properly.
Hence, we paint the outer side of the container of a solar cooker with black paint.
#13. Why do cricketers playing test match wear
white clothes? Ans: i. Different colours absorb heat in
different proportions. ii. White clothes reflect most of the radiant
heat falling on them. iii. Therefore, cricketers do not feel much
warmth even though it is hot outside. Hence, cricketers playing test match wear
white clothes. #14. Traditionally umbrellas are black in colour.
Why are they better than coloured ones?
Ans: i. A black surface absorbs about 98% of the incident heat radiation that falls on it.
ii. So, the black coloured umbrella absorbs the heat radiations and does not allow heat radiations to pass through.
Hence, black umbrellas are better than coloured ones.
#15. When you go for trekking, which coloured
cap do you prefer to use? Ans: White colour reflects most of the heat
radiations that falls on it.
Hence, when going for trekking, it is preferable to use white coloured cap.
#16. In the state of Rajasthan the temperatures
are very high in summer. Which colour for the roof is preferable in such regions?
Ans: i. In Rajasthan, where the temperatures are very high in summer, white colour for the roof is preferable.
ii. Due to this, the heat is reflected and the temperature of the house remains low.
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Std. IX: Science and Technology
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1.3 Change of state 1. Describe the change of phase or change of
state of matter when energy is supplied or taken away from a substance.
Ans: Change of phase:
i. The phase or state of matter can change when the temperature changes.
ii. When the temperature is increased, solid gets converted into liquid and liquid gets converted into gas.
iii. As the temperature rises, matter moves to a more active state.
iv. If energy is supplied (like increasing the
temperature or increasing the pressure) or if energy is taken away (like decreasing the temperature or decreasing the pressure), a physical change occurs.
*2. The smell of hot sizzling food reaches you
several meters away, but to get the smell from cold food, we have to go close. Why?
Ans: i. The gas molecules from the hot sizzling food mix with air easily as these molecules have a lot of energy. Hence, the smell of hot sizzling food spread around in all the directions and reaches several meters away.
ii. But the gas molecules from cold food cannot mix easily with air as these molecules have low energy due to its low temperature.
Hence, we have to go close to get the smell from cold food.
1.4 Evaporation, cooling by evaporation,
condensation 3. How does the condensation and evaporation
process keep the earth’s climate balanced? Ans: i. Condensation is the formation of liquid
drops from vapour. ii. It usually occurs when a parcel of rising
air expands and cools. iii. If it cools enough, some of the water
vapour molecules clump together at a faster rate.
iv. This process creates clouds which results in rain and snow, causing the earth’s climate to become cooler.
v. When cloud form, the heat removed from the earth’s surface through evaporation is released again in the atmosphere.
Thus, the earth’s climate remains balanced. 1.5 Sublimation #4. How would you separate the mixture of
sand and iodine crystals? Ans: i. In the mixture of sand and iodine
crystals, sand is not sublimatory while iodine is a sublimatory substance.
ii. By using sublimation method, we can separate the constituents of this mixture.
iii. Take this mixture in a china dish. iv. Put an inverted gas funnel over it. Place
a cotton plug in its stem. v. Heat the china dish. Iodine undergoes
sublimation and its vapours get condensed on the inner side of the funnel and cotton plug. Sand will remain in the china dish.
1.4 Evaporation, cooling by evaporation,
condensation 1. Evaporation Ans: i. Evaporation is the process by which a
liquid gets converted into the gaseous form at any temperature below its boiling point.
ii. All liquids can evaporate at room temperature and normal air pressure.
iii. In this process, atoms or molecules escape from the liquid and turn into vapour.
iv. There are always a few atoms or molecules with a lot of energy and some with very low energy.
Write short notes on
Answer in brief
+E+E
+E
Solid Liquid
Gas Plasma
Each addition of energy creates a change in state Inverted funnel
Iodine
China dish
Burner
Cotton plug
Mixture of sand and
iodine crystals
7
Chapter 01: World of Matter
v. The atoms or molecules with lot of energy are able to build up enough energy to get converted into gaseous state.
vi. Once they reach that energy level, they leave the liquid state. As a result the liquid gets evaporated.
vii. The rate of evaporation depends upon the surface area, temperature, humidity, wind speed, etc.
1.2 States of matter 1. Solids are rigid. Ans: i. In solids, the particles are closely
packed together and the forces holding these particles are strong.
ii. As a result, solids are almost incompressible.
iii. Their volume is not changed by any outside force and their shape remains unchanged even if an external force is applied.
Hence, solids are rigid. 2. Gases are more compressible than liquids. Ans: i. In liquids, the distance between the
neighbouring particles is less than those in the gases.
ii. In gases, the particles have high energy. They spread out to fill the container and
there are no forces to stop them from going apart.
iii. Thus, in gases, the particles are very far apart and the forces of attraction between the particles are extremely weak as compared to liquids.
Hence, gases are more compressible than liquids.
3. Some liquids like honey flow slowly, while
other liquids such as kerosene flow rapidly. Ans: i. The differences in flow rate is due to the
property of viscosity. ii. More viscous a liquid, less is its rate of
flow. iii. Honey is more viscous than kerosene. Hence, some liquids like honey flow slowly,
while other liquids such as kerosene flow rapidly.
*4. A gas exerts pressure on the walls of a
closed container. Ans: i. In the gaseous state, the particles of a
gas move with a very high speed in all directions.
ii. Due to this, the particles collide with the walls of the closed container, where a pressure is created.
Hence, a gas exerts pressure on the walls of a closed container.
*5. In LPG cylinder, the gas filled is in the
liquefied state. Ans: i. Gases are highly compressible. They
can be compressed into very small volumes by applying high pressure.
ii. This process converts the gas into a liquid.
iii. As a result, a large volume of gas can be compressed into a liquid and stored in small LPG cylinders. Such cylinders can be easily transported from one place to another.
Hence, in LPG cylinder, the gas filled is in the liquefied state.
1.4 Evaporation, cooling by evaporation,
condensation 6. The tea in a saucer gets cooled faster than
in a cup. Ans: i. When we pour very hot tea in a saucer,
it cools quickly due to the process of evaporation.
ii. Evaporation takes place only at the surface of a liquid.
iii. The rate of evaporation is directly proportional to the surface area of a liquid.
iv. The exposed surface area of the tea in saucer is greater than the exposed surface area of the tea in a cup.
Hence, tea poured in a saucer gets cooled faster than in a cup.
1.5 Sublimation 7. Naphthalene balls disappear over a period of
time, without leaving behind any solid particles.
Ans: i. Naphthalene balls sublimate at room temperature.
ii. All its molecules go into vapour phase without changing into liquid.
iii. This process takes place when naphthalene balls absorb heat energy from the surrounding, which occurs slowly but continuously.
Hence, naphthalene balls disappear over a period of time, without leaving behind any solid particles.
Give scientific reasons
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Std. IX: Science and Technology
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1. The state of matter having a definite shape and
volume. 2. The fourth state of matter. 3. A substance which is used as fuel in vehicles. 4. A substance which is used as ideal domestic
fuel in our home. Answers 1. Solid 2. Plasma 3. CNG (Compressed Natural Gas) 4. LPG (Liquefied Petroleum Gas) 1. Two objects can occupy the same space at the
same time. 2. When kerosene and water are mixed together,
water will form the upper layer. 3. The particles of a solid cannot move much. 4. Some liquids flow easily as compared to other
liquids. 5. More viscous liquids flow easily. 6. Liquids do not have a definite volume. 7. Gases cannot be compressed easily. 8. It is easier to walk through water than air. 9. Water freezes at 100 C. 10. The absorption of energy from the surrounding
reduces the temperature of the surrounding. 11. The rate of evaporation is not affected by
change in humidity. Answers 1. False: Two objects cannot occupy the same
space at the same time. 2. False: When kerosene and water are mixed
together, kerosene will form the upper layer. 3. True 4. True 5. False: Less viscous liquids flow easily. 6. False: Liquids have a definite volume. 7. False: Gases can be compressed easily. 8. False: It is easier to walk through air than water. 9. False: Water freezes at 0 C. 10. True 11. False: The rate of evaporation is affected by
change in humidity (i.e., it decreases with increase in humidity).
1. Water, Kerosene, Sugar, Milk 2. Stone, Common salt, Ice, Oil 3. Mercury, Hydrogen, Oxygen, Nitrogen 4. Camphor, Iodine, Water, Ammonium chloride Answers 1. Sugar: Others are liquids. 2. Oil: Others are solids. 3. Mercury: Others are gases. 4. Water: Others are sublimatory substances. 1. Solids 2. Rigid solids 3. Elastic solids 4. Liquids 5. Less viscous liquids 6. Highly viscous liquids 7. Gases 8. Sublimatory substances Answers 1. Blackboard, Ice 2. Stone, Iron 3. Rubber band, Spring 4. Milk, Oil 5. Water, Kerosene 6. Honey, Lubricants 7. Hydrogen, Oxygen 8. Iodine, Camphor 1. Wooden block: Solid :: Milk: ……. 2. Stone: Rigid :: Spring: ….. 3. Dust: Solid :: Carbon dioxide: …… 4. Solid: Incompressible :: Gas: ..….. 5. Water: Liquid :: Water vapour: …….. 6. Melting point of solid oxygen: 218.4 °C ::
Melting point of glucose: ..……. 7. Boiling point of water: .......... :: Freezing point
of water: 0 °C Answers 1. Liquid 2. Elastic 3. Gas 4. Compressible 5. Gas 6. 150 °C 7. 100 °C
State whether the following statements are true or false. If false, rewrite the correct statement.
T F
Find the odd man out
Give two examples of
Complete the analogy
Name the following
9
Chapter 01: World of Matter
1.
Column I Column II
i. Solids a. High compressibility
ii. Liquids b. Incompressible
iii. Gases c. Low compressibility Ans: (i – b), (ii – c), (iii – a) 2.
Column I Column II
i. Solid converts into liquid a. Evaporation
ii. Gas converts into liquid b. Freezing
iii. Liquid converts into gas c. Melting
iv. Liquid converts into solid d. Condensation Ans: (i – c), (ii – d), (iii – a), (iv – b) *3.
State of matter
A
B
1. Gas a. Soil i. Milk
2. Solid b. Kerosene ii. Oxygen
3. Liquid c. Carbon
monoxide iii. Peas
Ans: (1 – c - ii), (2 – a - iii), (3 – b - i) 1. Solids and Liquids Ans:
Solids Liquids
i. Solids have definite shape.
Liquids do not have definite shape.
ii. Solids are almost incompressible.
Liquids are less compressible.
iii. Solids do not flow. Liquids flow.
Eg. Sugar, stone Water, milk 2. Liquids and Gases Ans:
Liquids Gases i. Liquids have definite
volume. Gases do not have definite volume.
ii. Liquids have very low compressibility.
Gases have high compressibility.
iii. Liquids flow upto certain extent.
Gases flow everywhere in the available space.
Eg. Water, kerosene Hydrogen, oxygen 3. Solids and Gases Ans:
Solids Gases i. Solids have definite
shape. Gases do not have definite shape.
ii. Solids have definite volume.
Gases do not have definite volume.
iii. Solids are almost incompressible.
Gases are highly compressible.
Eg. Table, iron Nitrogen, Oxygen 4. Evaporation and Boiling Ans:
Evaporation Boiling i. It takes place at all
temperatures below the boiling point of the liquid.
It takes place only at the boiling point of the liquid.
ii. It causes cooling. It does not cause cooling.
1. Sample structure of a solid Ans: 2. Effort needed to compress solid, liquid and
gas Ans:
Match the columns
Distinguish between the following pairs
More Less
Effort Needed to Compress
GasSolid Liquid
Draw neat & labelled diagrams of the following
Solid particles
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Std. IX: Science and Technology
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3. Condensation due to the expansion of air Ans: 4. Condensation due to direct cooling of air Ans: 1. In the following figure, water changes into
ice: i. Which type of change is observed in
the process? ii. For this change of state, is energy
released or absorbed? Ans: i. Changing of water into ice is a physical
change. ii. In freezing (i.e., in conversion of water
to ice), energy is taken away from water. So, water releases energy to get converted into ice.
2. In the following figure, water changes to
hydrogen peroxide: i. Which type of change is observed in
the process? ii. Does the process involve change in
basic chemical structure of water? Ans: i. In the given process, chemical change is
observed. ii. Yes, the process involves change in
basic chemical structure of water as the water molecule (H2O) is converted to hydrogen peroxide molecule (H2O2).
3. Observe the following figure which shows the heating of ammonium chloride:
i. Name the process that occurs when ammonium chloride changes directly from solid state to gaseous state.
ii. Name other two substances which will show same behaviour as that of ammonium chloride when heated.
Ans: i. Sublimation ii. Camphor and iodine #1. Classify the following into solids, liquids
and gases: Air, bench, kerosene, bag, bottle, chalk, brass, water vapour, blackboard, dust, table, soil, chair, water, door, pen, milk, eraser, petrol, book, windowpanes, ice, diesel, carbon dioxide, cupboard, oxygen, mercury.
Ans:
Solids Liquids Gases
Bench, bag, bottle, chalk, brass, blackboard, dust, table, soil, chair, door, pen, eraser, book, windowpanes, ice, cupboard
Kerosene, water, milk, petrol, diesel, mercury
Air, water vapour, carbon dioxide, oxygen
#2. Suggest one scientific word for all of the
following changes: i. Solid wax converts into liquid wax. ii. Ice changes into water. iii. A plastic bowl kept near the flame,
changes its shape. iv. Frozen butter is kept outside the
refrigerator. Ans: Melting
Water Ice
H2O H2O2
Questions Based on Diagram
Miscellaneous
Liquid waterdroplets
Rising air parcel
Ice
Water
Inverted funnel
Ammonium chloride solidified
China dish
Burner
Cotton plug
Ammonium chloride
11
Chapter 01: World of Matter
Activity … II (Textbook page no. 1) Ans: i. No, we cannot count the number of
particles present in a piece of chalk. ii. The cotton cloth becomes wet due to
absorption of the liquid. iii. Yes, we can break the stream of water
with our fingers. iv. No, it is not possible to fill any more
liquid in the bottle as it is already filled up to the brim. There is air in the space which was earlier occupied by water.
Activity … III (Textbook page no. 2) Ans: i. The pebble will sink in water because
the density of the pebble is greater than the density of water. However, the plastic spoon will not sink in water because it has less density than water.
ii. Dry wood, ice, leaves, kerosene, oil, etc. are some substances which float on water.
Activity … IV (Textbook page no. 3 and 4) Ans: Observation: i. The liquids come down in the order of
decreasing speed as follows: kerosene > water > milk > honey ii. Among the four liquids, honey is the
most viscous and kerosene is the least viscous liquid.
iii. Kerosene, water and milk take the shape of the container faster.
iv. Honey forms layers and these layers take the shape of the container slowly.
Conclusion: Rate of flow of liquids depends on their viscosity. Activity ... V (Textbook page no. 4) Ans: i. Inflated balloons become heavier than
uninflated balloons because the air inside the inflated balloons also has some mass.
ii. a. Yes, we get the smell of incense stick in the other corner of the room.
b. When an incense stick is ignited, its material starts burning. The fragrance present in the incense stick is converted into gaseous state and spreads in all directions.
c. As gas molecules move faster than liquid or solid, they reach from one corner of a room to the other corner easily and so a person at the other corner gets its smell.
iii. Perfume is a volatile substance (easily escapes into air). Thus, the molecules of the perfume spread everywhere in the surrounding air. So, Sabiha can smell the perfume though she is sitting in a far off corner.
Activity … VI (Textbook page no. 5) Ans: i. Small droplets of the water are
observed on the inner surface of the lid because water vapours from the tea get condensed.
ii. In winter morning, the temperature of atmosphere is very low. The coconut oil freezes at this temperature and becomes solid. In the summer morning, the temperature of atmosphere is higher as compared to winter. Thus, oil does not freeze and remains in the liquid state.
Activity … VII (Textbook page no. 7) Ans: i. The wet handkerchief kept in the open
space would dry up faster. ii. The puddle will reduce in size due to
evaporation of water present in it. iii. We feel cold sensation at the site where
spirit is applied. iv. We pour very hot tea in a saucer to cool
it rapidly. By doing so, the exposed surface area increases and the rate of evaporation also increases which makes the tea cool faster.
v. a. The water kept in an earthen pot becomes cool due to the process of evaporation.
b. Large number of pores are present on the surface of earthen pot. Water comes out continuously from these pores into the outside environment.
c. As a result, evaporation takes place and the temperature of water in the pot decreases.
Hence, the water kept in an earthen pot (matka) becomes cool even in summer.
Activity … VIII (Textbook page no. 8) Ans: i. Camphor is a sublimatory substance. It
sublimates at room temperature and changes into gaseous state slowly. Due to this, camphor becomes smaller in size and finally disappears.
ii. Naphthalene balls sublimate at room temperature. They absorb heat energy from the surrounding and get converted into gaseous form. Naphthalene present in the gaseous form gets mixed with the air due to which the bad odour in the toilet reduces. So, naphthalene balls are kept in the toilets.
Activities
12
Std. IX: Science and Technology
12
Activity … IX (Textbook page no. 8) Ans: Ammonium chloride is a sublimatory
substance. When heated, solid ammonium chloride changes directly into gaseous state without changing into liquid state. Ammonium chloride, thus, gets deposited inside the inverted funnel and on the cotton plug.
1. Two vessels contain different types of
liquids A and B. If density of A is two times that of B and volumes of both the liquids taken in the vessels are the same, then which liquid has less mass?
Ans: Liquid B has less mass. 2. Why does the temperature of a substance
remain constant while changing from one state to another?
Ans: When a substance changes from one state to another, heat provided to the substance is utilised in increasing the distance between the molecules of the substance. However, the energy of the molecules (which is directly related to the temperature) does not increase.
Therefore, the temperature of a substance remains constant while changing from one state to another.
3. X and Y are two substances. They are given
same quantity of heat. X changes its state from solid to liquid. Y changes its state from solid to gas.
i. Can X change its state from liquid to gas when more heat is given?
ii. What kind of substance is Y? Ans: i. If more heat is given, then X can change
its state from liquid to gas. ii. Y is a sublimatory substance. 4. Complete the following chart:
Ans: 1. Solids
2. Liquids
3. Condense into liquids. Type I: Problems based on
Density(d) =Mass(m)
Volume(v)
#1. What is the density of a wooden block of
mass 4 grams and dimensions of
2 cm 3 cm 1 cm?
Ans: Given: m = 4 g, l = 2 cm,
b = 3 cm, h = 1 cm
To find: d = ?
Formula: i. v = l b h
ii. d = m
v
Solution:
From formula (i),
v = 2 cm 3 cm 1 cm
= 6 cm3
From formula (ii),
d = 3
4g
6cm = 0.67 g/cm3
The density of wooden block = 0.67 g/cm3 2. The mass of an iron block is 158 g and
density is 7.9 g/cm3. Calculate the volume of the block.
Ans: Given: m = 158 g, d = 7.9 g/cm3
To find: v = ?
Formula: density (d) = mass(m)
volume(v)
Solution:
From formula,
v = m
d
= 3
158g
7.9g/cm = 20 cm3
The volume of iron block = 20 cm3
3. The density of an object is 3.0 g/cm3 and its
volume is 8 cm3. Calculate the mass of the object.
Ans: Given: v = 8 cm3, d = 3.0 g/cm3
To find: m = ?
Solved Examples
HOTS
Melt into liquids. Sublimate into gases.
Matter
Gases
can be convertedinto
Evaporate into gases.Freeze into solids.
can be convertedinto
1 2
can be
3
13
Chapter 01: World of Matter
Formula: density (d) = mass(m)
volume(v)
Solution: From formula,
m = d v
= 3.0 g/cm3 8 cm3
= 24 g
Mass of the object = 24 g
Type II: Problems based on (F 32) 5
9= C
4. The temperature of an object is 20 °C.
Express this temperature in degree Fahrenheit.
Ans: Given: Temperature in degree Celsius (C) = 20 °C
To find: Temperature in degree Fahrenheit (F) = ?
Formula: (F 32) 5
9= C
Solution: From formula,
(F 32) 5 = 9C 5F – 160 = 9C 5F = 9C +160
5F = 9 20 +160 = 180 +160 = 340
F = 340
5 = 68 F
Temperature in degree Fahrenheit = 68 F 5. The temperature of an object is 95 F.
Express this temperature in degree Celsius. Ans: Given: Temperature in degree Fahrenheit
(F) = 95 F To find: Temperature in degree Celsius (C) = ?
Formula: (F 32) 5
9 = C
Solution: From formula,
C = (95 32) 5
9
= 63 5
9
= 7 5 = 35 °C
Temperature in degree Celsius = 35 C
Type I
1. The mass and volume of an object are 50 g and 25 cm3 respectively. Calculate the density of that object.
2. The volume and the density of an object is
18 cm3 and 4 g/cm3 respectively. Calculate the mass of that object.
3. Find the volume of an object having mass 27 g
and density 3 g/cm3. Type II 4. Express the following temperatures in degree
Fahrenheit.
i. 45 °C ii. 60 °C
iii. 15 °C iv. 70 °C 5. Express the following temperatures in degree
Celsius.
i. 104 °F ii. 122 °F
iii. 194 °F iv. 50 °F 1. 2 g/cm3
2. 72 g
3. 9 cm3
4. i. 113 °F ii. 140 °F
iii. 59 °F iv. 158 °F
5. i. 40 °C ii. 50 °C
iii. 90 °C iv. 10 °C Additional Theory Questions 1. Write the formula to calculate density of a
substance from its mass and volume.
Ans: Refer Answer the following questions in one sentence each Q.2. (Formula)
2. Explain why solids are incompressible.
Ans: Refer Give scientific reasons Q.1.(i) and (ii).
Practice Problems
Answers to Practice Problems
14
Std. IX: Science and Technology
14
Memory Map
Have definite shape and volume.
Almost incompressible.
Particles are compact and close together.
Different phases orstates of matter
Energy is supplied
Energy is taken away
Liquids
Energy is supplied
Energy is taken away
Solids
Have definite volume butdo not have definite shape.
Have very lowcompressibility.
Particles are little morespread out as compared tosolids.
Gases
Do not have definite shapeand volume.
Have high compressibility(i.e., can be easilycompressed).
Particles are very far apart.
Change in state Change in state Change in state
Solid Liquid Gas
Change in state Solids can be converted to: Liquids Melting Gases Sublimation
Change in state Liquids can be convertedto: Gases Evaporation Solids Freezing
Change in state Gases can be converted to: Liquids Condensation
Matter Made up of very tiny particles that
attract each other Occupies space Has volume and mass