This document discusses the nature of matter and its different states. It begins by defining matter as anything that has mass and occupies space. It then describes the particulate nature of matter and how particles are in continuous motion and attract each other. The three common states of matter are identified as solids, liquids, and gases. A variety of experiments are presented to demonstrate the properties of each state, as well as how matter can change between states through processes like evaporation and condensation.
Best PowerPoint presentation on NCERT class 9 Atoms and Molecules as per CBSE syllabus it covers full chapter with all information.
By Raxit Gupta
9C
KENDRIYA VIDYALAYA BALLYGUNGE
Chapter - 2, Is matter around us pure?, Science, Class 9Shivam Parmar
I have expertise in making educational and other PPTs. Email me for more PPTs at a very reasonable price that perfectly fits in your budget.
Email: parmarshivam105@gmail.com
Chapter - 2, Is matter around us pure?, Science, Class 9
PURE SUBSTANCES
WHAT IS A MIXTURE?
HOMOGENEOUS MIXTURE
HETEROGENEOUS MIXTURE
DIFFERENCE BETWEEN MIXTURES AND COMPOUNDS
SOLUTION
PROPERTIES OF SOLUTION
DIFFERENT TYPES OF SOLUTIONS
CONCENTRATION
SUSPENSION
COLLOIDAL SOLUTION
PROPERTIES OF COLLOIDS
TYNDALL EFFECT
COMPONENTS OF COLLOID
SEPARATING THE COMPONENTS OF A MIXTURE
PHYSICAL CHANGE
CHEMICAL CHANGE
Every topic of this chapter is well written concisely and visuals will help you in understanding and imagining the practicality of all the topics.
By Shivam Parmar (Entrepreneur)
This PPT is based on Physics on Chapter Motion. In this you will find every thing of that chapter with great images. in this PPT their are many animation and images .
thank you
Best PowerPoint presentation on NCERT class 9 Atoms and Molecules as per CBSE syllabus it covers full chapter with all information.
By Raxit Gupta
9C
KENDRIYA VIDYALAYA BALLYGUNGE
Chapter - 2, Is matter around us pure?, Science, Class 9Shivam Parmar
I have expertise in making educational and other PPTs. Email me for more PPTs at a very reasonable price that perfectly fits in your budget.
Email: parmarshivam105@gmail.com
Chapter - 2, Is matter around us pure?, Science, Class 9
PURE SUBSTANCES
WHAT IS A MIXTURE?
HOMOGENEOUS MIXTURE
HETEROGENEOUS MIXTURE
DIFFERENCE BETWEEN MIXTURES AND COMPOUNDS
SOLUTION
PROPERTIES OF SOLUTION
DIFFERENT TYPES OF SOLUTIONS
CONCENTRATION
SUSPENSION
COLLOIDAL SOLUTION
PROPERTIES OF COLLOIDS
TYNDALL EFFECT
COMPONENTS OF COLLOID
SEPARATING THE COMPONENTS OF A MIXTURE
PHYSICAL CHANGE
CHEMICAL CHANGE
Every topic of this chapter is well written concisely and visuals will help you in understanding and imagining the practicality of all the topics.
By Shivam Parmar (Entrepreneur)
This PPT is based on Physics on Chapter Motion. In this you will find every thing of that chapter with great images. in this PPT their are many animation and images .
thank you
HEAT
TEMPERATURE
LAND BREEZE
EFFECT OF HEAT
MEASUREMENT OF TEMPERATURE
CLINICAL THERMOMETERS
DIGITAL THERMOMETERS
SEA BREEZE
TRANSFER OF HEAT
CONDUCTION
CONVECTION
CONDUCTORS AND INSULATORS
RADIATION
DARK COLOURED SURFACES AND COLOURED SURFACES
WIND
This chapter is for class 9 based on CBSE curriculum in which physical nature of matter, its characteristics are discussed along with states of matter, their inconversion, scales of temperature and difference between boiling and evaporation and factors affecting evaporation with inforgraphics and key points.
HEAT
TEMPERATURE
LAND BREEZE
EFFECT OF HEAT
MEASUREMENT OF TEMPERATURE
CLINICAL THERMOMETERS
DIGITAL THERMOMETERS
SEA BREEZE
TRANSFER OF HEAT
CONDUCTION
CONVECTION
CONDUCTORS AND INSULATORS
RADIATION
DARK COLOURED SURFACES AND COLOURED SURFACES
WIND
This chapter is for class 9 based on CBSE curriculum in which physical nature of matter, its characteristics are discussed along with states of matter, their inconversion, scales of temperature and difference between boiling and evaporation and factors affecting evaporation with inforgraphics and key points.
ALTERNATIVE LEARNING SYSTEM
DISTRICT III
Name:
Level: Date:
Community Learning Center:
32200174 / SURIGAO WEST CENTRAL ELEMENTARY SCHOOL ALS Facilitator:
DANICA M. BAIDIANGO Score:
LEARNING STRAND 2 Scientific Literacy and Critical Thinking Skills
Content Standard: Demonstrate understanding on various biological concepts and their applications
Performance Standard D: Apply biological science concepts in different life situations
Learning Competency:
a. Identify the different sense organs (LS2SC-BC-PSD-LE/AE/JHS-19);
b. Relate the structure of the sense organs to its functions (LS2SC-BC-PSD-LE/AE/JHS-19);
c. Demonstrate healthful habits in taking care of the sense organs (LS2SC-BC-PSD-LE/AE/JHS-21)
d. Describe the causes and symptoms of some diseases associated with the sense organs, e.g. • Eyes: ocerthalmium (night blindness), conjunctivitis, stye, • sore eyes, lesions of the eyes, foreign body • Nose: adenoids, foreign body • Ears: otitis, foreign body • Tongue/mouth: oral thrush (singaw), Herpes simplex • Skin: carbuncle, boils (pigsa), dermatitis and fungal infections
CONTENT: OUR SENSE ORGAN: Lesson 1- The Organs of Sight and Hearing
References: ALS A&E Our Sense Organ.pdf (page 4-17)
A. LET’S SEE WHAT YOU ALREADY KNOW!
I- Multiple Choice. Encircle the correct answer.
1. Our eye is our organ for _______________.
a. smell
b. hearing
c. vision
d. touch
2. A thin layer of tissue that lines your eyelids and nasal cavity is called _____________.
a. lining
b. mucous membrane
c. skin
d. dermis
3. The innermost layer of cell inside your eye is called the _______________.
a. mucous membrane b. conjunctiva c. retina d. choroid
4. The visible part of your ear is called ______________.
a. ear b. auricle c. flaps d. shell
5. You hear sounds through ________________.
a. vibration b. music c. noise d. light
6. The smallest bones of your body are found in your _______________.
a. eyes b. nose c. mouth d. ears
7. Olfaction pertains to your sense of _________________.
a. smell
b. touch
c. sight
d. taste
8. _______________ are groups of cells inside your mouth that detect the taste of the food you eat.
a. tongue b. teeth c. taste buds d. saliva
9. The biggest sense organ of your body is your ___________________.
a. nose b. lips c. skin d. eyes
10. Your sense of touch is also called ______________ sense.
a. olfaction
b. vision
c. balance
d. tactile
II- Write the corresponding sense organ affected by the following disorders or diseases. Write eye, ear, nose, tongue, or skin on the space provided before each number.
_______________ 1. Carbuncle
_______________ 2. Otitis Media
_______________ 3. Rhinitis
_______________ 4. Sty
_______________ 5. Aguesia
B. CONCEPT NOTES
LESSON 1
The Organs of Sight and Hearing
How do our eyes see?
Figure 1.1
Our eye has many parts and each one of them helps you see.
Try blinking one
It is my friend's PPT for School Science Seminar made by Me. He stand at 1st position in the Seminar. Its the 1st chapter of class 9th Science of CBSE. Just View and You will definitely like it.
Kids Club Smilecatch // Family Fun Activities 06Smilecatch
We can learn in family while having fun. This is the philosophy in our kids club smilecatch. Activities able to develop your children while having fun.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
CBSE Class 9 Science Chapter-1 Matter in our surroundings
1. Matter in Our Surroundings
By
N.Aarthi
B.E, M.Tech
SASTRA UNIVERSITY
2. Contents
• What is matter?
• Physical nature of matter.
• Characteristics of particles of matter.
• States of matter.
• Can matter change its state?
• Evaporation.
• Multiple choice questions.
3. What is Matter
• Air we breathe
• Food we eat
• Clouds
• Stars
• Plants and animals
• Drop of water
• Particle of sand
4.
5. Physical nature of Matter
Matter is made up of particles.
Example: You mix salt/sugar in water. It spreads
throughout water.
Observation: Particles of salt/sugar fills gaps
between particles of water.
6.
7. How small are these particles of
Matter?
Activity:
Step 1: Add crystals of potassium permanganate in
100ml water.
Step 2: Take 10ml of above and mix it in 90ml clear
water.
Step 3: Repeat above steps.(Dilution)
Is the water still colored?
8. Observation:
Few crystals can color large volumes of water.
One crystal contains millions of particles.
They keep dividing themselves into smaller
particles.
10. Characteristics of Particles of Matter
• Particles have space between them.
• Particles are continuously moving.
• Particles attract each other.
11. Particles Of Matter have space between them.
Particles of salt,sugar,dettol,potassium
permanganate got evenly distributed in water.
Conclusion: There is enough space between
particles of matter.
12. Particles Of Matter are continuously
moving
Activity 1:
• Put an unlit incense stick in a corner of your
class.
• How close do you have to go near it so as to
get its smell?
• Now light the incense stick. What happens?
• Do you get the smell sitting at a distance?
• Record your observations.
14. Solution
• One has to go very close to get the smell of the
unlit incense stick.
• After lighting the incense stick, smoke started to
coming out of it.
• Yes now, we can get smell of incense stick sitting
at a distance.
• This shows that, Matters consist of small particles
which are moving continuously. This means that
particles of matter possess kinetic energy.
• Smell of lighted incense stick diffuse with air
present in air and reaches to us sitting at a
distance.
15. Activity 2
• Take two glasses/beakers filled with water.
• Put a drop of blue or red ink slowly and carefully
along the sides of the first beaker and honey in
the same way in the second beaker.
• Leave them undisturbed in your house or in a
corner of the class.
• Record your observations.
• What do you observe immediately after adding
the ink drop?
• What do you observe immediately after adding a
drop of honey?
• How many hours or days does it take for the color
of ink to spread evenly throughout the water?
17. Solution
• Ink started mixing with water immediately after adding
which is visible in the form of many thread like
structures.
• Honey slowly directed towards bottom of water.
• It takes about one hour to spread color of ink
throughout the water.
• This happens because Ink has about equal or slightly
higher density than that of water, so ink started
immediately mixing with water, because particles of
matters are moving continuously.
• Density of honey is very high than that of water, so
honey started to direct towards bottom.
• Because particles of matters are continuously moving,
thus after some time particles of ink and water get
mixed with each other.
18. Activity 3
Drop a crystal of copper sulphate or potassium permanganate into a
glass of hot water and another containing cold water. Do not stir the
solution. Allow the crystals to settle at the bottom.
• What do you observe just above the solid crystal in the glass?
Solid crystals starts mixing in the water in the form of thread like
structures.
• What happens as time passes?
Coming of thread like structures in cold water is slower than that of in
the hot water.
• What does this suggest about the particles of solid and liquid?
As time passes, crystal getting dissolved in water both hot and cold.
But it takes more time to get crystal dissolved in cold water than that
of hot water.
20. This suggest that, matters are made up of tiny
particles and these particles are in motion
continuously.
• Does the rate of mixing change with
temperature? Why and how?
Rate of mixing increases with increase in
temperature. This is because of heat particles of
matter gets more kinetic energy and they starts
moving faster.
21. Particles Of Matter attract each other.
Activity 1
• Play this game in the field? make four groups and
form human chains as suggested:
• The first group should hold each other from the
back and lock arms .The second group should
hold hands to form a human chain.
• The third group should form a chain by touching
each other with only their finger tips.
• Now, the fourth group of students should run
around and try to break the three human chains
one by one into as many small groups as possible.
• Which group was the easiest to break? Why?
22.
23. Solution :
The fourth group of students was the easiest to
break.
This is because students are not holding hands
or bounded even with their finger tips.
This means that there was no bonding force
present in forth group. And could be broken
easily.
25. Activity 2
• Take an iron nail, a piece of chalk and a rubber
band.
• Try breaking them by hammering, cutting or
stretching.
• In which of the above three substances do you
think the particles are held together with
greater force?
Solution
Iron nail did not break, thus its particles of iron
are held together with greater force.
26.
27. Activity 3
• Open a water tap, try breaking the stream of
water with your fingers.
• Were you able to cut the stream of water?
• What could be the reason behind the stream of
water remaining together?
Solution :
• Now, we did not be able to cut the stream of
water.
• The reason behind the stream of water remaining
together is that the particles of water are held
together with force of attraction.
30. Solid state
Activity:
• Collect the following articles? a pen, a book, a
needle and a piece of wooden stick.
• Sketch the shape of the above articles in your
notebook by moving a pencil around them.
• Do all these have a definite shape, distinct
boundaries and a fixed volume?
• What happens if they are hammered, pulled or
dropped?
• Are these capable of diffusing into each other?
• Try compressing them by applying force. Are you
able to compress them?
31.
32. Solution
• Yes all these have a definite shape, distinct
boundaries and a fixed volume.
• Book is torn when pulled strongly.
• Pen and piece of wooden stick are broken
when hammered.
• None is capable of diffusing into each other.
• None is compressible.
33. Liquid state- Activity
Collect the following:
(a) water, cooking oil, milk, juice, a cold drink.
(b) containers of different shapes. Put a 50 mL mark on these
containers using a measuring cylinder from the laboratory.
What will happen if these liquids are spilt on the floor?
Ans: All the liquids flow after spilt on the floor.
Measure 50 mL of any one liquid and transfer it into different
containers one by one. Does the volume remain the same?
Ans: Yes, volume remains same after transferring the liquid into
different containers.
36. Does the shape of the liquid remain the same ?
Ans: Liquid gets the shape of container.
When you pour the liquid from one container
into another, does it flow easily?
Ans: Yes all liquids flow easily.
Conclusion: Liquids have no fixed shape but has
fixed volume. It takes shape of container in
which they are kept.
37. Liquids are incompressible yet in industrial applications
water can be tremendously compressed and used to do
things like cut through metal.
38. Aquatic animals breathe under water. How?
They can breathe due to presence of dissolved
oxygen in water.
Conclusion: solids, liquids and gases can diffuse
into liquids.
Property: Rate of diffusion of liquids is higher
than that of solids. Because in liquid state,
particles move freely and have greater space
between them compared with solid state.
39. Gaseous state
Activity
• Take three 100 mL syringes and close their nozzles by
rubber corks.
• Remove the pistons from all the syringes.
• Leaving one syringe untouched, fill water in the second and
pieces of chalk in the third.
• Insert the pistons back into the syringes. You may apply
some Vaseline on the pistons before inserting them into the
syringes for their smooth movement.
• Now, try to compress the content by pushing the piston in
each syringe.
40.
41. • What do you observe? In which case was the piston
easily pushed in?
Syringe that left untouched is pushed easily.
• What do you infer from your observations?
This shows that, there was air in syringe left untouched,
which is a gas and is compressible.
Gas is easily compressible while water (liquid) and solid
(chalk) cannot be compressed, i.e. incompressible.
44. Can matter change its state?
Activity: Effect of change of temperature
• Take about 150 g of ice in a beaker and suspend a laboratory thermometer so that
its bulb is in contact with the ice.
• Start heating the beaker on a low flame.
• Note the temperature when the ice starts melting.
• Note the temperature when all the ice has converted into water.
• Record your observations for this conversion of solid to liquid state.
• Now, put a glass rod in the beaker and heat while stirring till the water starts
boiling.
• Keep a careful eye on the thermometer reading till most of the water has
vaporized.
• Record your observations for the conversion of water in the liquid state to the
gaseous state.
45. (a) Conversion of ice to water
(b) conversion of water to water vapour
46. Solution
• Temperature was 0 degree Celsius when ice
starts melting.
• Temperature remained 0 degree Celsius till all
ice melted.
• Temperature starts rising after melting of ice.
• Temperature stopped rising after reaching
at 100 degree Celsius.
• Again temperature started rising after
vaporization of all water.
• This shows that supply of continuous heat while
melting of ice is used in change of phase i.e.
from solid to liquid.
47. • And supply of continuous heat while vaporization of
water is used in change of phase, i.e. from liquid to
vapour of water.
• Heat used in melting of ice is called Latent heat of
Fusion.
• The temperature at which a liquid starts boiling at
atmospheric pressure is known as its boiling point.
• And heat used in vaporization of water is called Latent
heat of Vaporization.
48. Activity
• Take some camphor or ammonium chloride. Crush it and
put it in a china dish.
• Put an inverted funnel over the china dish.
• Put a cotton plug on the stem of the funnel, as shown in
Fig. 1.7.
• Now, heat slowly and observe.
• What do you infer from the above activity?
49.
50. Solution:
• After some time camphor or ammonium gets
deposited on the inner surface of funnel.
• This shows that camphor or ammonium chloride
converted directly from solid to gas and from gas
to solid.
• This process is called sublimation.
• A change of state directly from solid to gas on
heating is called sublimation.
• Direct change of gas to solid on cooling is called
deposition.
51. Effect of change of pressure
• Applying pressure and reducing temperature
can liquefy gases.
What is solid Co2?
It is stored under high pressure. Solid co2 gets
converted directly to gaseous state on decrease
of pressure. Solid co2 is also known as dry ice.
58. Evaporation
Liquid changes to vapour without reaching
boiling point
Example: water left uncovered, wet clothes dry
up.
Liquids have high kinetic energy .
So it is able to break away from forces of
attraction of other particles.
Evaporation: Phenomenon of change of liquid
into vapours at any temperature below boiling
point is called Evaporation.
61. Activity
• Take 5 mL of water in a test tube and keep it near a window or under a fan.
• Take 5 mL of water in an open china dish and keep it near a window or under a
fan.
• Take 5 mL of water in an open china dish and keep it inside a cupboard or on a
shelf in your class.
• Record the room temperature.
• Record the time or days taken for the evaporation process in the above cases.
• Repeat the above three steps of activity on a rainy day and record your
observations.
• What do you infer about the effect of temperature, surface area and wind velocity
(speed) on evaporation?
62.
63. Solution
• Water kept in china dish near window evaporated
in about half an hour.
• While water kept in test tube took about one
hour to get evaporated.
• Water kept in china dish inside cupboard took
more than one hour to get evaporated.
• In rainy days, double time was taken to get water
evaporated.
• This activity shows that Rate of evaporation
increases with increase in surface area and wind
speed and decreases with increase in humidity.
64. How does evaporation cause cooling?
• Particles of liquid absorb energy from
surrounding to regain energy lost during
evaporation.
• This absorption of energy from surroundings
make the surrounding cold.
• Example: Nail polish remover
• It gains energy from your palm and evaporates
causing palm to feel cool.
66. Why should we wear cotton in
summer?
• Cotton , good absorber of water helps in
absorbing sweat and exposing it to
atmosphere for easy evaporation.
67. Why we notice water droplets in glass
containing ice cold water?
• Water vapour present in air on coming in
contact with cold glass of water loses energy
and gets converted to liquid state, which we
see as water droplets
68. Extra Questions
1. Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought,
cold, lemon water, smell of perfume.
Solution: The following substances are matter:
Chair, Air, Almonds, Lemon water.
69. 2. Give reasons for the following observation:
The smell of hot sizzling food reaches you
several meters away, but to get the smell from
cold food you have to go close.
Solution: Particles in the air, if fueled with
higher temperatures, acquire high kinetic energy
which aids them to move fast over a stretch.
Hence the smell of hot sizzling food reaches a
person even at a distance of several meters.
70. 3. A diver is able to cut through water in a
swimming pool. Which property of matter does
this observation show?
Solution: The diver is able to easily cut through
the water in the swimming pool because of the
weak forces of attraction between water
molecules. It is this property of water that
attributes to easy diving.
71. 4. What are the characteristics of the particles of
matter?
Solution: The characteristics of particles of
matter are:
(a) Presence of intermolecular spaces between
particles
(b) Particles are in constant motion
(c) They attract each other
72. 5. The mass per unit volume of a substance is called
density. (density=mass/volume). Arrange the
following in the order of increasing density - air,
exhaust from the chimneys, honey, water, chalk,
cotton and iron.
Solution: The following substances are arranged in
the increasing density:
Air
Exhaust from chimney
Cotton
Water
Honey
Chalk
Iron
73.
74. 7. Give reasons
a) A gas fills completely the vessel in which it is
kept.
b) A gas exerts pressure on the walls of the
container.
c) A wooden table should be called a solid.
d) We can easily move our hand in the air but to
do the same through a solid block of wood we
need a karate expert
75. Solution:
a) Kinetic energy possessed by gas particles is very high
which allows them to randomly move across all directions
when contained, hence the particles fills the gas vessel
entirely.
b) Gas molecules possess high kinetic energy, due to
which they are under constant motion inside the
container in random directions which causes them to hit
the walls of the container and hence create vibrations.
These collisions with the walls of the container generate
pressure.
c) A wooden table should be called a solid as it possesses
all the properties of a solid such as: • Definite size and
shape • Intermolecular attraction between closely packed
particles. • It is rigid and cannot be compressed
76. d) Molecules in gases are loosely packed as
compared to solid molecules which are densely
packed. Hence we are easily able to break the
force of attraction when we move our hand
through air but find it difficult to break through
a solid (because of greater forces of attraction
between molecules) which a karate expert is
able to smash with the application of a lot of
force.
77. 8. Liquids generally have a lower density than
solids. But you must have observed that ice
floats on water. Find out why?
Solution: Density of ice is less than the density
of water. The low density of ice can be
attributed to the small pores it has which allows
it to trap air hence ice floats on water.
78. 9. Convert the following temperature to Celsius
scale:
a. 300K
b. 573K
Solution:
a. 0°C=273K
300K= (300-273)°C = 27°C
b. 573K= (573-273)°C = 300°C
79. 10. What is the physical state of water at:
a. 250°C
b. b. 100°C ?
Solution:
(a) At 250°C - Gaseous state since it is beyond its
boiling point.
(b) (b) At 100°C - It is at the transition state as
the water is at its boiling point. Hence it
would be present in both liquid and gaseous
state
80. 11. For any substance, why does the
temperature remain constant during the change
of state?
Solution:
It is due to the latent heat as the heat supplied
to increase the temperature of the substance is
used up to transform the state of matter of the
substance hence the temperature stays
constant.
81. 12. Suggest a method to liquefy atmospheric
gases.
Solution: It can be achieved by either increasing
the pressure or decreasing the temperature
which ultimately leads to the reduction of
spaces between molecules.
82. 13. Why does a desert cooler cool better on a
hot dry day?
Solution: It is because the temperature is high
and it is less humid on a hot dry day which
enables better evaporation. High levels of this
evaporation provide better cooling effects.
83. 14. How does the water kept in an earthen pot
(matka) become cool during summer?
Solution: An earthen pot is porous in nature.
These tiny pores facilitate penetration of water
and hence their evaporation from the pot
surface. The process of evaporation requires
energy which is contributed by water in the pot
as a result of which water turns cooler.
84. 15. Why does our palm feel cold when we put
on some acetone or petrol or perfume on it?
Solution: Acetone, petrol, and perfume are
volatile substances that get evaporated when
they come in contact with air. Evaporation is
facilitated as it uses energy from palm hence
leaving a cooling effect on our palms.
85. 16. Why are we able to sip hot tea or milk faster
from a saucer rather than a cup?
Solution: A saucer has a larger surface area than
a cup which promotes quicker evaporation
hence the tea or milk in a saucer cools down
faster.
86. 17. What type of clothes should we wear in
summer?
Solution: In summer, it is preferred to wear light-
colored cotton clothes because light color
reflects heat and cotton materials have pores
that absorb sweat, facilitating their evaporation
hence causing a cooling effect in the skin
87. Exercise
1. Convert the following temperature to Celsius
scale.
(a) 293K
(b) 470K
Solution: 0°C=273K
(a) 293K= (293 - 273)°C = 20°C
(b) 470K= (470 - 273)°C = 197°C
88. 2. Convert the following temperatures to the
Kelvin scale.
(a) 25°C
(b) 373°C
Solution: 0°C = 273K
(a) 25°C = (25+273)K = 298K
(b) 373°C = (373+273)K = 646K
89. 3. Give reason for the following observations:
(a) Naphthalene balls disappear with time without leaving
any solid.
(b) We can get the smell of perfume while sitting several
metres away.
Solution:
(a) At room temperature, naphthalene balls undergo
sublimation wherein they directly get converted from a solid
to a gaseous state without having to undergo the
intermediate state, i.e., the liquid state.
(b) Molecules of air move at a higher speed and have large
intermolecular spaces. Perfumes comprise of flavoured
substances that are volatile which scatters quickly in air,
becoming less concentrated over a distance. Hence we are
able to smell perfume sitting several metres away.
90. 4. Arrange the following in increasing order of
forces of attraction between the particles -
water, sugar, oxygen.
Solution:
Oxygen (gas) < water (liquid) < sugar
(solid)
91. 5. Give two reasons to justify -
(a) Water at room temperature is a liquid.
(b) An iron almirah is a solid at room temperature.
Solution:
(a) Transition in the states of matter of water occurs at 0°C
and 100°C. At room temperature, water is in the liquid
state, thereby exhibiting all the properties of a liquid such
as
• Water flows at this temperature
• It has a fixed volume and it takes the shape of its container
(b) The melting and boiling points of iron are as high as
1538°C and 2862°C respectively. The room temperature is
about 20-25 °C. Hence iron almirah is a solid at room
temperature.
92. 6. Why is ice at 273K more effective in cooling
than water at the same temperature?
Solution: Water at this temperature(273K) is
less effective than ice as ice can readily form
water through absorption of ambient heat
energy as opposed to water which does not
exhibit this property as it already possesses
additional latent heat of fusion so does not
require extra heat. Hence ice cools rapidly
compared to water at the same temperature.
93. 7. What produces more severe burns, boiling
water or steam?
Solution: Steam produces severe burns. It is
because it is an exothermic reaction that
releases high amount of heat which it had
consumed during vaporization.