case study science class 9 chapter 1

Class 9 Science Case Study Questions Chapter 1 Matter in our Surroundings

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Case study Questions in Class 9 Science Chapter 1 are very important to solve for your exam. Class 9 Science Chapter 1 Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving Class 9 Science Case Study Questions  Chapter 1 Matter in our Surroundings

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In CBSE Class 9 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Matter in our Surroundings Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 9 Science  Chapter 1 Matter in our Surroundings

Case Study/Passage-Based Questions

Case Study 1: There are three states of matter – solid, liquid, and gas.

Solids  have a definite shape, distinct boundaries, and fixed volumes, that is, have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force but it is difficult to change their shape, so they are rigid.

Liquids  have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid.

Gas  has an indefinite shape and no fixed volume. Gas gets the shape and volume of the container.Gas has a very low density and hence is light. Gas can flow easily and hence is called fluid.

i.) Which of the following state of matter takes the shape of the container in which it is filled?

d.) Both b and c

Answer: d.) Both b and c

ii.) Distance between particles of matter least in

d.) None of these

Answer: a.) Solid

iii.) Compressibility is least in case of

Case Study 2: Matter is anything that occupies space and has mass. It exists in various forms, such as solid, liquid, and gas. The physical properties of matter, such as shape, size, and state, can be observed and measured. The particles that makeup matter are constantly in motion, and their motion determines the state of matter. In a solid, the particles are tightly packed and have a fixed shape and volume. In a liquid, the particles are close together but can move past each other, giving the substance a fixed volume but no fixed shape. In a gas, the particles are far apart and move freely, allowing the substance to occupy any volume and shape. Matter can undergo changes in its state through the processes of evaporation, condensation, melting, and freezing. Understanding the properties and behavior of matter is essential for studying various scientific phenomena and practical applications in our daily lives.

What is matter? a) Anything that occupies space and has mass b) Anything that is visible to the naked eye c) Anything that is in a solid state d) Anything that is in a gaseous state Answer: a) Anything that occupies space and has mass

What determines the state of matter? a) Physical properties b) Chemical properties c) The motion of particles d) The color of the substance Answer: c) The motion of particles

How are particles arranged in a solid? a) Far apart and move freely b) Close together but can move past each other c) Tightly packed and have a fixed shape d) Tightly packed but have no fixed shape Answer: c) Tightly packed and have a fixed shape

What is the behavior of particles in a gas? a) They are far apart and move freely b) They are close together but can move past each other c) They are tightly packed and have a fixed shape d) They are tightly packed but have no fixed shape Answer: a) They are far apart and move freely

What processes can matter undergo to change its state? a) Evaporation, condensation, melting, and freezing b) Dissolution, combustion, sublimation, and oxidation c) Fermentation, photosynthesis, respiration, and digestion d) Oxidation, reduction, precipitation, and ionization Answer: a) Evaporation, condensation, melting, and freezing

Hope the information shed above regarding Case Study and Passage Based Questions for Class 9 Science Chapter 1 Matter in our Surroundings with Answers Pdf free download has been useful to an extent. If you have any other queries about CBSE Class 9 Science Matter in our Surroundings Case Study and Passage Based Questions with Answers, feel free to comment below so that we can revert back to us at the earliest possible By Team Study Rate

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Case Study Questions Class 9 Science Matter in our Surroundings

Case study questions class 9 science chapter 1 matter in our surroundings.

CBSE Class 9 Case Study Questions Science Matter in our Surroundings. Important Case Study Questions for Class 9 Exam. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Matter in our Surroundings.

At Case Study Questions there will given a Paragraph. In where some Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks or 4 marks.

CBSE Case Study Questions Class 9 Science – Matter in our Surroundings

Case study 1:.

1.) A matter is anything that has mass and occupies space. Pen, paper, clips, sand, air, ice, etc. are different forms of matter. Every matter is made up of small particles. These particles are so tiny that they can’t be seen with naked eyes. Let’s see about the different characteristics of particles of matter.

• All matter is made up of very small particles.
• .Particles of matter has spaces between them.
• Particles of matter are continuously moving.
• Particles of matter attract each other.

Answer the following questions by referring above paragraph.

i.) Which of following is not matter?

c.) smell of perfume

d.) None of these

ii.) Thoughts coming in our mind are example of matter. True or false

c.) None of these

iii.) Which of the following is true about particles of matter?

a.) Particles of matter has spaces between them

b.) Particles of matter are continuously moving

c.) Particles of matter attract each other

d.) All of these

iv.) Give 5 examples of matter in our surroundings

v.) Enlist all properties of particles of matter

Answer key-1

iv.) pen, pencil, notebook, ice and water

v.) Different characteristics of particles of matter are

Case Study 2:

2.) There are three states of matter – solid, liquid and gas.

Solids have a definite shape, distinct boundaries and fixed volumes, that is, have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force but it is difficult to change their shape, so they are rigid.

Liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid.

Gas as has indefinite shape, no fixed volume. Gas gets the shape and volume of container.

Gas has very low density hence are light. Gas can flow easily and hence are called fluid.

i.) Which of the following state of matter takes shape of container in which it is filled?

d.) Both b and c

ii.) Distance between particles of matter least in

iii.) Compressibility is least in case of

iv.) Give properties of solids.

v.) Give properties of Gases.

Answer key-2

iv.) properties of solid are given below

• Solid has fixed volume.
• Solid has fixed shape.
• Solid has high density.
• Solids are heavy.
• Solid does not flow.

v.) Properties of gases are

• Gas has indefinite shape
• Gas has no fixed volume.
• Gas gets the shape and volume of container.
• Gas fills the container completely.
• Gas has very low density.
• Because of low density gas are light.
• Gas can flow easily and hence are called fluid.

Case Study 3:

3.) What happens inside the matter during change of state? On increasing the temperature of solids, the kinetic energy of the particles increases. Due to the increase in kinetic energy, the

Particles start vibrating with greater speed. The energy supplied by heat overcomes the forces of attraction between the particles. The particles leave their fixed positions and start moving more freely. A stage is reached when the solid melts and is converted to a liquid. The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

The temperature of the system does not change after the melting point is reached, till all the ice melts. This happens even though we continue to heat the beaker, that is, we continue to supply heat. This heat gets used up in changing the state by overcoming the forces of attraction between the particles. The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion. So, particles in water at 0 0 C (273 K) have more energy as compared to particles in ice at the same temperature.

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point. Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain enough energy to change into the vapour state. A change of state directly from solid to gas without changing into liquid state is called sublimation and the direct change of gas to solid without changing into liquid is called deposition.

i.) A change of state directly from solid to gas without changing into liquid state is called

a.) Sublimation

b.) Deposition

c.) Boiling point

ii.) The direct change of gas to solid without changing into liquid is called

iii.) The energy supplied by heat to solid is used to overcome the forces of attraction between the particles. True or false

iv.) Define melting point and boiling point

v.) Define latent heat of fusion

Answer key-3

iv.) The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.

v.) The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion.

Case Study 4:

4 .) Do we always need to heat or change pressure for changing the state of matter? Can you quote some examples from everyday life where change of state from liquid to vapour takes place without the liquid reaching the boiling point? In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the forces of attraction of other particles and gets converted into vapour. This phenomenon of change of a liquid into vapors at any temperature below its boiling point is called evaporation.

i.) Evaporation of liquid takes place at

a.) Boiling point

b.) Above boiling point

c.) Below boiling point

ii.) Evaporation takes place at surface of liquid because

a.) They are heavy as compare to other particles

b.) They have sufficient kinetic energy to break the force

c.) They are light weight as compare to other particles

iii.) During evaporation particles of liquid change into vapour

a.) From the surface

b.) From the bottom

c.) From all over the liquid

iv.) Define evaporation.

v.) Explain process of evaporation

Answer key-4

iv.) The phenomenon of change of a liquid into vapors at any temperature below its boiling point is called evaporation.

v.) In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the forces of attraction of other particles and gets converted into vapour. This phenomenon of change of a liquid into vapors at any temperature below its boiling point is called evaporation.

Case Study 5:

5.) You must have observed that the rate of evaporation increases with–

• an increase of surface area:
• We know that evaporation is a surface phenomenon. If the surface area is increased, the rate of evaporation increases. For example, while putting clothes for drying up we spread them out.
• an increase of temperature:

With the increase of temperature, more number of particles get enough kinetic energy to go into the vapour state.

In an open vessel, the liquid keeps on evaporating. The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation. This absorption of energy from the surroundings makes the surroundings cold. What happens when you pour some acetone (nail polish remover) on your palm? The particles gain energy from your palm or surroundings and evaporate causing the palm to feel cool. After a hot sunny day, people sprinkle water on the roof or open ground because the large latent heat of vaporization of water helps to cool the hot surface.

i.) Evaporation is surface phenomenon. True or false

ii.) As temperature increases the rate of evaporation is

a.) increases

b.) decreases

c.) remains constant

iii.) The rate of evaporation increases with

a.) Increase in wind speed

b.) Decrease in wind speed

c.) Does not have any effect from wind speed

iv.) What happens when you pour some acetone (nail polish remover) on your palm?

v.) We are able to sip hot tea from saucer than from cup. Why?

Answer key-5

iv.) The particles gain energy from your palm or surroundings and evaporate causing the palm to feel cool.

v.) We are able to sip hot tea from saucer than from cup. This is because saucer has large surface area, due to large surface area as compare to cut area tea evaporates at faster rate.

Thank you It helped me a lot

Why smell of Perfume is not a matter?

Because there is no particle

Because their are perfume particles suspended in air

These all case study questions are really helpful . Thanks

This is my first I was so nervous but these questions help me alot thank you

Smell of perfume is a matter because it have gas particles means perfume particles

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• Class 9 Science Case...

Class 9 Science Case Study Questions

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Download the app to get CBSE Sample Papers 2023-24, NCERT Solutions (Revised), Most Important Questions, Previous Year Question Bank, Mock Tests, and Detailed Notes.

If you are wondering how to solve class 9 science case study questions, then myCBSEguide is the best platform to choose. With the help of our well-trained and experienced faculty, we provide solved examples and detailed explanations for the recently added Class 9 Science case study questions.

You can find a wide range of solved case studies on myCBSEguide, covering various topics and concepts. Class 9 Science case studies are designed to help you understand the application of various concepts in real-life situations.

The rationale behind Science

Science is crucial for Class 9 students’ cognitive, emotional, and psychomotor development. It encourages curiosity, inventiveness, objectivity, and aesthetic sense.

In the upper primary stage, students should be given a variety of opportunities to engage with scientific processes such as observing, recording observations, drawing, tabulating, plotting graphs, and so on, whereas in the secondary stage, abstraction and quantitative reasoning should take a more prominent role in science teaching and learning. As a result, the concept of atoms and molecules as matter’s building units, as well as Newton’s law of gravitation, emerges.

Science is important because it allows Class 9 Science students to understand the world around us. It helps to find out how things work and to find solutions to problems at the Class 9 Science level. Science is also a source of enjoyment for many people. It can be a hobby, a career, or a source of intellectual stimulation.

Case study questions in Class 9 Science

The inclusion of case study questions in Class 9 science CBSE is a great way to engage students in critical thinking and problem-solving. By working through real-world scenarios, Class 9 Science students will be better prepared to tackle challenges they may face in their future studies and careers. Class 9 Science Case study questions also promote higher-order thinking skills, such as analysis and synthesis. In addition, case study questions can help to foster creativity and innovation in students. As per the recent pattern of the Class 9 Science examination, a few questions based on case studies/passages will be included in the CBSE Class 9 Science Paper. There will be a paragraph presented, followed by questions based on it.

Examples of Class 9 science class case study questions

Class 9 science case study questions have been prepared by myCBSEguide’s qualified teachers. Class 9 case study questions are meant to evaluate students’ knowledge and comprehension of the material. They are not intended to be difficult, but they will require you to think critically about the material. We hope you find Class 9 science case study questions beneficial and that they assist you in your exam preparation.

The following are a few examples of Class 9 science case study questions.

Class 9 science case study question 1

• due to its high compressibility
• large volumes of a gas can be compressed into a small cylinder
• transported easily
• all of these
• shape, volume
• volume, shape
• shape, size
• size, shape
• the presence of dissolved carbon dioxide in water
• the presence of dissolved oxygen in the water
• the presence of dissolved Nitrogen in the water
• liquid particles move freely
• liquid have greater space between each other
• both (a) and (b)
• none of these
• Only gases behave like fluids
• Gases and solids behave like fluids
• Gases and liquids behave like fluids
• Only liquids are fluids

Answer Key:

• (d) all of these
• (a) shape, volume
• (b) the presence of dissolved oxygen in the water
• (c) both (a) and (b)
• (c) Gases and liquids behave like fluids

Class 9 science case study question 2

• 12/32 times
• 18 g of O 2
• 18 g of CO 2
• 18 g of CH 4
• 1 g of CO 2
• 1 g of CH 4 CH 4
• 2 moles of H2O
• 20 moles of water
• 6.022  ×  1023 molecules of water
• 1.2044  ×  1025 molecules of water
• (I) and (IV)
• (II) and (III)
• (II) and (IV)
• Sulphate molecule
• Ozone molecule
• Phosphorus molecule
• Methane molecule
• (c) 8/3 times
• (d) 18g of CH ​​​​​4
• (c) 1g of H ​​​​​​2
• (d) (II) and (IV)
• (c) phosphorus molecule

Class 9 science case study question 3

• collenchyma
• chlorenchyma
• It performs photosynthesis
• It helps the aquatic plant to float
• It provides mechanical support
• Sclerenchyma
• Collenchyma
• Epithelial tissue
• Parenchyma tissues have intercellular spaces.
• Collenchymatous tissues are irregularly thickened at corners.
• Apical and intercalary meristems are permanent tissues.
• Meristematic tissues, in its early stage, lack vacuoles, muscles
• (I) and (II)
• (III) and (I)
• Transpiration
• Provides mechanical support
• Provides strength to the plant parts
• None of these
• (a) Collenchyma
• (b) help aquatic plant to float
• (b) Sclerenchyma
• (d) Only (III)
• (c) provide strength to plant parts

Cracking Class 9 Science Case Study Questions

There is no one definitive answer to Class 9 Science case study questions. Every case study is unique and will necessitate a unique strategy. There are, nevertheless, certain general guidelines to follow while answering case study questions.

• To begin, double-check that you understand the Class 9 science case study questions. Make sure you understand what is being asked by reading it carefully. If you’re unclear, seek clarification from your teacher or tutor.
• It’s critical to read the Class 9 Science case study material thoroughly once you’ve grasped the question. This will provide you with a thorough understanding of the problem as well as the various potential solutions.
• Brainstorming potential solutions with classmates or other students might also be beneficial. This might provide you with multiple viewpoints on the situation and assist you in determining the best solution.
• Finally, make sure your answer is presented simply and concisely. Make sure you clarify your rationale and back up your claim with evidence.

A look at the Class 9 Science Syllabus

The CBSE class 9 science syllabus provides a strong foundation for students who want to pursue a career in science. The topics are chosen in such a way that they build on the concepts learned in the previous classes and provide a strong foundation for further studies in science. The table below lists the topics covered in the Class 9 Science syllabus of the Central Board of Secondary Education (CBSE). As can be seen, the Class 9 science syllabus is divided into three sections: Physics, Chemistry and Biology. Each section contains a number of topics that Class 9 science students must study during the course.

CBSE Class 9 Science (Code No. 086)

Theme: Materials Unit I: Matter-Nature and Behaviour Definition of matter; solid, liquid and gas; characteristics – shape, volume, density; change of state-melting (absorption of heat), freezing, evaporation (cooling by evaporation), condensation, sublimation. Nature of matter:  Elements, compounds and mixtures. Heterogeneous and homogenous mixtures, colloids and suspensions. Particle nature and their basic units:  Atoms and molecules, Law of constant proportions, Atomic and molecular masses. Mole concept: Relationship of mole to mass of the particles and numbers. Structure of atoms:  Electrons, protons and neutrons, valency, the chemical formula of common compounds. Isotopes and Isobars.

Theme: The World of the Living Unit II: Organization in the Living World Cell – Basic Unit of life:  Cell as a basic unit of life; prokaryotic and eukaryotic cells, multicellular organisms; cell membrane and cell wall, cell organelles and cell inclusions; chloroplast, mitochondria, vacuoles, endoplasmic reticulum, Golgi apparatus; nucleus, chromosomes – basic structure, number. Tissues, Organs, Organ System, Organism: Structure and functions of animal and plant tissues (only four types of tissues in animals; Meristematic and Permanent tissues in plants).

Theme: Moving Things, People and Ideas Unit III: Motion, Force and Work Motion:  Distance and displacement, velocity; uniform and non-uniform motion along a straight line; acceleration, distance-time and velocity-time graphs for uniform motion and uniformly accelerated motion, derivation of equations of motion by graphical method; elementary idea of uniform circular motion. Force and Newton’s laws:  Force and Motion, Newton’s Laws of Motion, Action and Reaction forces, Inertia of a body, Inertia and mass, Momentum, Force and Acceleration. Elementary idea of conservation of Momentum. Gravitation:  Gravitation; Universal Law of Gravitation, Force of Gravitation of the earth (gravity), Acceleration due to Gravity; Mass and Weight; Free fall. Floatation:  Thrust and Pressure. Archimedes’ Principle; Buoyancy. Work, energy and power:  Work done by a Force, Energy, power; Kinetic and Potential energy; Law of conservation of energy. Sound:  Nature of sound and its propagation in various media, speed of sound, range of hearing in humans; ultrasound; reflection of sound; echo.

Theme: Food Unit IV: Food Production Plant and animal breeding and selection for quality improvement and management; Use of fertilizers and manures; Protection from pests and diseases; Organic farming.

PRESCRIBED BOOKS:

• Science-Textbook for class IX-NCERT Publication
• Assessment of Practical Skills in Science-Class IX – CBSE Publication
• Laboratory Manual-Science-Class IX, NCERT Publication
• Exemplar Problems Class IX – NCERT Publication

myCBSEguide: A true helper

There are numerous advantages to using myCBSEguide to achieve the highest results in Class 9 Science.

• myCBSEguide offers high-quality study materials that cover all of the topics in the Class 9 Science curriculum.
• myCBSEguide provides practice questions and mock examinations to assist students in the best possible preparation for their exams.
• On our myCBSEguide app, you’ll find a variety of solved Class 9 Science case study questions covering a variety of topics and concepts. These case studies are intended to help you understand how certain principles are applied in real-world settings
• myCBSEguide is that the study material and practice problems are developed by a team of specialists who are always accessible to assist students with any questions they may have. As a result, students may be confident that they will receive the finest possible assistance and support when studying for their exams.

So, if you’re seeking the most effective strategy to study for your Class 9 Science examinations, myCBSEguide is the place to go!

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Case Study Questions of Chapter 1 Matter in our Surroundings PDF Download

Case study Questions on Class 9 Science Chapter 1 are very important to solve for your exam. Class 9 Science Chapter 1 Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving case study-based questions for Class 9 Science Chapter 1 Matter in our Surroundings

In CBSE Class 9 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Matter in our Surroundings Case Study Questions With answers

Here, we have provided case-based/passage-based questions for Class 9 Science  Chapter 1 Matter in our Surroundings

Case Study/Passage-Based Questions

Question 1:

There are three states of matter – solid, liquid, and gas.

Solids  have a definite shape, distinct boundaries, and fixed volumes, that is, have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force but it is difficult to change their shape, so they are rigid.

Liquids  have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid.

Gas  has an indefinite shape and no fixed volume. Gas gets the shape and volume of the container.

Gas has very low density hence is light. Gas can flow easily and hence is called fluid.

i.) Which of the following state of matter takes shape of the container in which it is filled?

d.) Both b and c

Answer: d.) Both b and c

ii.) Distance between particles of matter least in

d.) None of these

Answer: a.) Solid

iii.) Compressibility is least in case of

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Class 9 Science Chapter 1 Case Based Questions - Matter in Our Surroundings

(I) Read the given passage and answer the questions that follows based on the passage and related studied concepts. Matter is anything that occupies space and has mass. Matter is classified into solid, liquid and gas. In solid state particles are closely packed and have very strong force of attraction, particles can only vibrate and rotate around fixed positions. In liquid state, particles are less closely packed and have strong force of attraction but less than solids, particles can move throughout the liquid. In Gaseous state, particles are far apart with weak force of attraction and are in state of constant random motion. Gases can be easily compressed where as solids and liquids are incompressible. Q1: An inflated balloon is placed in refrigerator, what will happen? (a)  Balloon will shrink and particles will move faster and become closer. (b) Balloon will expand and particles will move faster and become far apart. (c)  Balloon will shrink, particles will move slower and become close together. (d) Balloon will expand, particles will move slower and come closer therefore, volume of balloon will decrease. Ans: (c)  Kinetic energy will decrease, so particles will move slower, become closer and volume of balloon will decrease.

Q2: When solid changes into vapours, the process is called. (a) Evaporation (b) Boiling (c)  Sublimation (d)  Vapourisation Ans:  (c)

Q3: A substance melts at 5°C and boils at 150°C. What will be its physical state at room temperature?  Ans:  Liquid

Q4: Why do we feel more cold after taking bath with hot water? Ans:  It is because hot water evaporates faster than cold water and cause more cooling.

Q2: What does AB represent? Ans:  It represents a mixture of liquid and vapours at boiling point of liquid.

Q3: Why does temperature remain constant at boiling point? Ans: It is because heat of vaporization is used to overcome force of attraction between particles of liquid.

Q4: What does BC represent? Ans:  It represents vapour state and particles absorb heat and become more energetic. The tempera-ture of gas will rise.

(III) Read the following information and answer the questions based on information and related studied concepts Substance – 1. is brittle. Substance – 2. melts at 5°C and boils at 150°C. Substance – 3. has high melting point of 800°C. Substance – 4. has melting point –169°C and boiling point –104°C.

Q1:  What is physical state of substance – 4 at –150°C and –100°C? Ans:  Substance 4 is liquid at –150°C and gas at –100°C.

Q2: What is physical state of substance – 1 and 3 at room temperature? Ans:  Substance 1 and 3 are solids at room tempera-ture.

Q3: What is physical state of substance – 2 at 100°? Ans:  It will be in liquid state.

Q4: Out of substances – 1, 2, 3, 4 which one has strongest force of attraction? Ans:  Substance 3 has strongest forces of attraction.

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NCERT Solutions for Class 9 Science Chapter 1 Matter in Our Surroundings

NCERT Solutions for Class 9 Science (chemistry) Chapter 1 Matter in Our Surroundings are given below. In these solutions, we have answered all the intext and exercise questions provided in NCERT class 9 science textbook. Class 9 NCERT Solutions Science Chapter 1 provided in this article are strictly based on the CBSE syllabus and curriculum. Students can easily download these solutions in PDF format for free from our app.

Class 9 Science Chapter 1 Textbook Questions and Answers

Intext Questions

Question 1:  Which of the following are matter? 

Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume. 

Answer: Chair, air, almonds, and cold-drink are matters. 

Explanation: Things that occupy space and have some mass are called matter. Since chair, air, almonds and cold-drink occupy some space and have some mass, so these are matter.

Question 2: Give reasons for the following observation: 

The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close. 

Answer: The smell of hot sizzling food reaches severed meters away, as the particles of hot food have more kinetic energy and hence the rate of diffusion is more than the particles of cold food.

  Smell of anything comes because of gases emanating from the given thing. The smell reaches to us because of diffusion of gas. The rate of diffusion increases with increase in temperature. This happens because of higher kinetic energy due to higher temperature. That is why smell of hot sizzling food reaches to us from several feet. On the other hand, the kinetic energy of gases emanating from cold food is low because of lower temperature. Due to this, we need to move closer to a cold food to take its smell.

Question 3: A diver is able to cut through water in a swimming pool. Which property of matter does this observation show? 

Answer: A diver is able to cut through water in a swimming pool. This shows that the particles of water have intermolecular space and has less force of attraction.

 Question 4: What are the characteristics of particles of matter? 

Answer: The characteristics of particles of matter are:

• Particles of matter have spaces between them. 
• Particles of matter are continuously moving. 
• Particles of mater attract each other.

Question 1:  The mass per unit volume of a substance is called density (density = mass/volume). Arrange the following in order of increasing density − air, exhaust from chimney, honey, water, chalk, cotton, and iron. 

Answer: The given substances in the increasing order of their densities can be represented as: 

Air < Exhaust from chimney < Cotton < Water < Honey < Chalk < Iron  

Explanation:  Air is the mixture of gases. Chimney exhaust is also a mixture of gases; along with some heavier particles, such as ash. This makes the density of chimney exhaust more than air. Cotton is a porous solid and which has lot of air trapped within pores. This makes its volume more than water. Therefore, it is less dense than water.

Question 2:  (a) Tabulate the differences in the characteristics of states of matter. (b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

Answer:  (a) The differences in the characteristics of states of matter are given in the following table. 

The difference in the characteristics of the three states of matter.

(b) Rigidity:  The greatest force of attraction between particles and close packing of particles make solids rigid. Rigidity is one of the unique properties of solids. Because of rigidity, a solid can resist from getting distorted. Because of rigidity a solid has definite shape and volume. Rigidity is negligible in fluid and gas.

Compressibility:  Compressibility is one of the most important characteristics of gas. Because of lot of space between particles, a gas can be compressed to a great extent.

Liquid and solid cannot be compressed because of the least space between their particles.

Fluidity:  The ability to flow is called fluidity. The less force of attraction and more space between particles make liquid and gas to flow. That’s why liquid and gas are called fluid.

Filling of a gas container:  Liquids do not fill a gas container completely, while gases fill the gas container completely in which it is kept. This is because the particles of gas can move in all the directions.

Shape:  Solids have fixed shape. Liquid and gas take the shape of the container in which they are kept. This happens because of less force of attraction and more kinetic energy between particles of liquids and negligible force of attraction and highest kinetic energy between particles of gas.

Kinetic energy:  The kinetic energy of particles of solid is the minimum. They only vibrate at their fixed position. The kinetic energy of particles of liquid is more than that of solid. But they can slide above one another. The kinetic energy of particles of gas is the maximum.

Density:  The mass per unit volume of a substance is called density. The density of solid is highest, of liquid is less than solid and of gas is minimum.

Question 3:  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 air, but to do the same through a solid block of wood, we need a karate expert.

Answer:  (a) There is little attraction between particles of gas. Thus, gas particles move freely in all directions. Therefore, gas completely fills the vessel in which it is kept.

(b)  Because of negligible force of attraction between particles of gas, the particles of gas have the highest kinetic energy. These properties enable the particles of gas to move in all directions and hit the walls of container from all sides. Because of this a gas exerts pressure on the walls of the container in which it is kept.

(c) A wooden table has a definite shape and volume. It is very rigid and cannot be compressed i.e., it has the characteristics of a solid. Hence, a wooden table should be called a solid.

(d) Particles of air have large spaces between them. On the other hand, wood has little space between its particles. Also, it is rigid. For this reason, we can easily move our hands in air, but to do the same through a solid block of wood, we need a karate expert.

Since, air is gas, so its particles are loosely packed and there is negligible force of attraction between its particles. Because of that we can easily move our hand in air. But wood is a solid, so the force of attraction between its particles is greatest. The particles of wooden block are closely packed. That’s why we cannot move our hand through a solid block of wood. However, a karate expert can exert required pressure to break the great force of attraction of the particles of a solid wooden block.

Question 4:  Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why. 

Answer: During freezing of water, some space between the particles of water is left vacant with some air trapped between them. These empty spaces having air in them makes the density of ice; lower than that of water. That’s why ice floats on water.

Question 1: Convert the following temperatures into the Celsius scale. (a) 300 K (b) 573 K

Answer: (a) 300 K = (300 − 273)°C = 27°C (b) 573 K = (573 − 273)°C = 300°C

Question 2: What is the physical state of water at (a) 250°C  (b) 100°C

Answer: (a) Water at 250°C exists in gaseous state.

(b) At 100°C, water can exist in both liquid and gaseous form. At this temperature, after getting the heat equal to the latent heat of vaporization, water starts changing from liquid state to gaseous state.

Question 3:  For any substance, why does the temperature remain constant during the change of state? 

Answer: During a change of state, the temperature remains constant. This is because all the heat supplied to increase the temperature is utilized (as latent heat) in changing the state by overcoming the forces of attraction between the particles. Therefore, this heat does not contribute in increasing the temperature of the substance. 

Question 4:  Suggest a method to liquefy atmospheric gases. 

Answer:  Atmospheric gas is liquefied by increasing pressure and decreasing temperature.

PAGE NO. 10

Question 1:  Why does a desert cooler cool better on a hot dry day?

Answer: Desert cooler works on the basis of evaporation. In hot and dry days the moisture level is very low in atmosphere which increases the rate of evaporation. Because of faster evaporation, cooler works well. That’s why desert cooler cool better on a hot dry day.

When a liquid evaporates, the particles of the liquid absorb energy from the surroundings to compensate the loss of energy during evaporation. This makes the surroundings cool. 

In a desert cooler, the water inside it is made to evaporate. This leads to absorption of energy from the surroundings, thereby cooling the surroundings. Again, we know that evaporation depends on the amount of water vapour present in air (humidity). If the amount of water vapour present in air is less, then evaporation is more. On a hot dry day, the amount of water vapour present in air is less. Thus, water present inside the desert cooler evaporates more, thereby cooling the surroundings more.  That is why a desert cooler cools better on a hot dry day. 

Question 2:  How does water kept in an earthen pot (matka) become cool during summers?

Answer: Water from porous wall of earthen pot evaporates continuously, which lowers the temperature of water kept in the earthen pot. In summer moisture level is very low in the atmosphere, which increases the rate of evaporation as evaporation is inversely proportional to the moisture level in atmosphere. That is why in summer water kept in earthen pot becomes cool.

Question 3: Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Answer: When we put some acetone or petrol or perfume on our palm, it evaporates. During evaporation, particles of the liquid absorb energy from the surrounding or the surface of the palm to compensate for the loss of energy, making the surroundings cool. Hence, our palm feels cold when we put some acetone or petrol or perfume on it.

Question 4: Why are we able to sip hot tea or milk faster from a saucer than a cup? 

Answer: When hot tea or milk is kept in a saucer, the liquid is exposed over a larger surface area as compared to in case of the liquid being kept in a cup. The larger surface area enables the faster cooling. That’s why we are able to sip hot tea or milk faster from a saucer rather than from a cup.

Question 5:   What type of clothes should we wear in summers? 

Answer: In summer, it is preferred to wear light-coloured cotton clothes because light colour reflects heat and cotton materials have pores that absorb sweat, facilitating their evaporation hence causing a cooling effect in the skin.

Question 1: Convert the following temperatures into the Celsius scale. (a) 293 K (b) 470 K

Answer: Temperature in Celsius scale = Temperature in Kelvin scale – 273

(a) 293K= (293 – 273)°C = 20°C

(b) 470K= (470 – 273)°C = 197°C

Question 2: Convert the following temperatures into the Kelvin scale.  (a) 25°C (b) 373°C

Answer: Temperature in Kelvin scale = Temperature in Celsius scale + 273

(a) 25°C = (25+273)K = 298K

(b) 373°C = (373+273)K = 646K

Question 3: Give reasons 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.

Answer: (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) Perfumes vaporize very fast and its vapours diffuse into air easily. That is why we can smell perfume sitting several meters away. 

Question 4: Arrange the following in increasing order of forces of attraction between the particles – water, sugar, oxygen.

Answer:  Oxygen < Water < Sugar.

Explanation: Oxygen is a gas, thus force of attraction is negligible between particles. Water is a liquid, thus force of attraction between particles is more than liquid and less than solid. Sugar is a solid, thus force of attraction between particles is greatest.

Question 5: What is the physical state of water at — (a) 25°C                       (b) 0°C                               (c) 100°C?

Answer: (a) At 25°C – water is in liquid state. (b) At 0°C – water is in solid state. (c) At 100°C – water is in transition state, i.e. in liquid and gas both.

Question 6: Give two reasons to justify: (a) water at room temperature is a liquid. (b) an iron almirah is a solid at room temperature.

Answer: (a) At room temperature (25 °C), water is a liquid because it has the following characteristic of liquid:

(i) Water has definite volume, but not definite shape as it takes the shape of the container in which it is kept. (ii) Water flows at room temperature.  

(b) An iron almirah is a solid at room temperature because: (i) It has definite shape. (ii) It has definite volume.

Question 7: Why is ice at 273 K more effective in cooling than water at the same temperature?

Answer: At 273K ice requires more latent heat to melt into water, while water at 273K requires less latent heat; to come to the room temperature. So, ice at 273 K is more effective in cooling than water at the same temperature.

Question 8: What produces more severe burns, boiling water or steam?

Answer: Steam produces more severe burns than boiling water. This is because steam has more energy than boiling water, present in it in the form of latent heat of vaporization.

Question 9: Name A, B, C, D, E and F in the following diagram showing change in its state:

Answer: A: Melting (or) fusion (or) liquefaction B: Evaporation (or) vaporization C: Condensation D: Solidification E: Sublimation F: Sublimation

Class 9 Science NCERT Solutions Chapter 1 Matter in Our Surroundings

CBSE Class 9 Science NCERT Solutions Chapter 1 helps students to clear their doubts and to score good marks in the board exam. All the questions are solved by experts with a detailed explanation that will help students complete their assignments & homework. Having a good grasp over CBSE NCERT Solutions for Class 9 Science will further help the students in their preparation for board exams and other competitive exams such as NTSE, Olympiad, etc.

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Matter can be defined as something that has mass and occupies space. For instance, air, water, oxygen, fruits, etc. All these are considered as matter in our surroundings and are classified as solids, liquids and gases. They are made up of microscopic particles called molecules which are tightly, loosely and very loosely packed, respectively. Being the elementary lesson of Class 9 Science , you must be thorough on the same. In this regard, Matter in Our Surroundings Class 9 Notes by Vedantu can be of immense help. Along with textbooks, make sure to refer to this material for revision purposes and also achieve desired scores in exams. Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths Students who are looking for the better solutions, they can download Class 9 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.

The revision notes of Chapter 1, Class 9 Science subject are present here. The students can simply study these notes before the exam to get a comprehensive overview of teh whole chapter.

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Introduction

Everything around us is formed of the matter: a pencil, a pen, a table, the food we consume, the clothes we wear, the walls of our homes. But what is the matter?

Anything that occupies space has mass, and can be sensed by our senses is considered the matter. In other words, the term "matter" refers to all of the substances and materials that make up the cosmos.

Composition of Matter

According to ancient Indian philosophers, the matter is made up of five constituents or tattvas, according to studies found in our sacred books and scriptures.

Illustration 1. How many different ways did ancient Indian philosophers classify matter?

a. $2$ 

b. $6$ 

c. $7$ 

d. $5$ 

Ans: $\left( D \right)$

Matter is made up of Particles  

Now that we have defined matter let us ask ourselves the question – What is a matter made up of? 

All matter comprises very small particles. 

All matter can be broken up in a similar manner to get very small particles. 

Hence we now conclude that all matter is made up of small particles.

(Image will be uploaded soon)

Illustration 2. Which of the following are matters? 

Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, the smell of perfume.

Ans: chair, air, almond, cool drink

Properties of Matter 

Small particles of matter make up all matter. Some features are shared by all of these particles. A theory called Kinetic Theory of Matter explains forth these features.

Simply said, The Kinetic Theory of Matter States is a theory that describes how matter changes throughout time.

a. All matter is made up of tiny particles.

b. There is space between these particles.

c. The particles are in constant motion.

d. The particles are attracted to one another.

Particles of Matter have space between them 

Small particles make up matter, and these particles have small spaces between them.

These areas are not visible to the naked eye, yet particles of other matter can pass through them without changing their volume.

Particles of Matter are continuously moving 

Particles in the matter are constantly moving. Three types of motion were seen in the matter particles.

a. Translatory Motion - It occurs when particles move in straight lines and change direction without losing energy after interacting with another particle or the container's wall. When compared to liquids, translational motion is greatest in gases and least in solids.

b. Rotational motion: When particles travel about their own axis, this is known as rotational motion . This motion is comparable to the earth's rotation around its axis. In gases and liquids, the rotational motion will be quite high.

c. Vibrational Motion - When particles move back and forth around a central point. Solids have the greatest amount of motion because the particles are held in a hard framework.

Particles of Matter attract each other 

1. The force with which they attract one another differs depending on the matter.

2. The force is modest in some types of materials (waste paper, matchsticks) (as we can tear or break them easily).

3. The force is large in other types of material (iron nail) (as we cannot break the nail easily).

Illustration 3. When sugar dissolves in water, what happens to it? What happens to the sugar? What does the dissolution of sugar in water tell you about the nature of matter?

a. When sugar dissolves in water, the solid sugar crystals are broken up into microscopic particles.

b. The sugar particles interact with the water particles in the gaps between them (to form a sugar solution).

c. Sugar dissolving in water indicates that the stuff (in this case, sugar and water) is made up of minute particles. There are voids between the particles of stuff (in this case, water).

Diffusion 

“The mixing and spreading out of a substance with another substance due to the movement or motion of its particles is called diffusion.” 

The process of one substance diffusing into another continues until a homogenous mixture is achieved. Let's have a look at an example.

Put a crystal of potassium permanganate (purple colour) in one of the beakers that is full of water. Gradually, you'll notice that the purple-colored crystal begins to diffuse or dissolve into water, and after a while, it turns purple.

Diffusion in Gases 

Gases have a very fast diffusion rate. Because gas particles move very swiftly in all directions, this is the case.

Examples \[1:\]

Even from a long distance, the smell of food being prepared in the kitchen reaches us.

The smell of hot, sizzling food reaches us even when we are a long way away, but we must approach close to get the smell of cold food.

This is because the rate of diffusion of hot gases is substantially faster than the rate of diffusion of cold gases released by cold food.

Example \[2:\] 

When someone opens a bottle of perfume in one corner of a room, the scent soon travels throughout the space.

When a perfume bottle is opened, the liquid perfume soon turns into vapour (or gas).

The scent vapours flow quickly in all directions in the air, mixing with the air particles and spreading across the room.

Example 

The diffusion of a strong-smelling chemical (ethyl mercaptan) found in the cooking gas into the air detects the leaking of cooking gas (LPG) in our houses.

Diffusion in Liquids 

Liquid diffusion is slower than gas diffusion. This is due to the fact that particles in liquids move slower than particles in gases.

Solid in Liquid 

When a crystal of potassium permanganate is placed in the bottom of a beaker of water, the purple colour of the potassium permanganate progressively spreads throughout the water.

The liquid in Liquid: 

When a drop of ink is dropped into a beaker of water, the colour of the ink spreads across the entire water in the beaker; this is due to the diffusion of ink particles into water.

Gases like carbon dioxide and oxygen are necessary for aquatic plants and animals to survive. The carbon dioxide and oxygen gases in the air (or atmosphere) diffuse into and dissolve in water (ponds, lakes, and rivers). Aquatic plants use dissolved carbon dioxide to prepare food through photosynthesis, whereas aquatic animals breathe using dissolved oxygen in the water.

Diffusion in Solids 

Solid-state diffusion is an extremely slow process.

Example : 

If we write something on a blackboard and then leave it filthy for a long time (say, 10 to 15 days), cleaning the blackboard becomes quite tough. This is owing to the fact that certain chalk particles have dispersed into the backboard's surface.

When two metal blocks are closely linked together and left undisturbed for several years, the particles of one metal permeate into the other metal. Gases dissipate quickly. A gas's rate of diffusion is proportional to the square root of its density.

Force of Attraction (or Cohesion) 

Between the particles of matter, there is an attractive force that binds them together. The force of attraction is the attraction between particles of the same substance (or cohesion).

In general, the force of attraction is greatest in solid matter particles and least in gaseous matter particles.

Illustration 4. Analyse the effects of diffusion in different states of matter, such as solid, gas, and liquid.

Ans: $\text{Solid}<\text{Liquid}<\text{Gases}$ 

         Slow        Fast            Very Fast

States of Matter

Solids have a definite volume and shape. They are more difficult to break than liquids and gases.

Liquids have a specific volume but not a specific shape. They take on the shape of the container they're housed in.

Gases do not have a defined shape or volume. They take up all of the available space and take on the shape of the container in which they are kept.

Plasma - At extremely high temperatures, the plasma state is a fused and ionic condition of matter (like the core of the sun, stars). Because it is made up of positive ions and a pool of electrons, the fused ionic mass is neutral. Around 99 per cent of the universe is made up of fused ionic matter.

Illustration 5. 

a. Give two reasons why wood is a solid material.

b. ‘A material has a known volume but no known shape.' Indicate if the substance is solid, liquid, or gaseous.

c. Describe the physical state of matter that can be squeezed readily.

d. ‘A substance has both a definite shape and a defined volume.' Which physical state does this statement represent? A substance has neither a fixed shape nor a fixed volume. State whether it is a solid, a liquid or a gas. 

e. Give two reasons to justify that: 

i. Water is a liquid at room temp. 

ii. An iron almirah is solid.

a. Wood has

i. fixed shape, and 

ii. fixed volume 

b. Liquid 

c. Gas 

d. Solid 

e. Gas 

i. Fixed volume but no fixed shape 

ii. Fixed shape and fixed volume.

Rigid and Fluid 

Rigid is a word that denotes "unbending" or "inflexible." Because it is unbending or inflexible, a stone is stiff. Fluid is defined as "a material that flows easily" and requires the use of a vessel (container) to keep it contained.

A solid is a kind of stuff that is unyielding. Solids have a tendency to keep their shape when subjected to external force due to their rigidity. As a result, rigidity is the primary distinguishing feature of solids. As a result, rigidity is the primary distinguishing feature of solids. Solids don't need to be kept in a container. Two common solids are a brick and a log of wood.

A liquid is a fluid type of stuff that fills the container's lower half. Liquids must be kept in a container because they are fluids. Because liquids have a well-defined surface, they can be stored in an open container. The liquid will not spontaneously escape from the open container. Water and milk are two prevalent liquids found in our environment.

Gas is a form of stuff that fills the entire container in which it is contained. Gases, like liquids, require a container to keep them contained. Because gas has no open surface, it must be stored in a closed container. If gas is kept in an open container, it will escape. Gases are frequently stored in airtight gas cylinders because of this. Cooking gas (LPG), for example, is stored in airtight metal cylinders. We can conclude from this discussion that fluids include both liquids and gases. Fluidity is a property of liquids and gases that allows them to flow smoothly. When exposed to external stress, liquids and gases change shape quickly due to their fluidity.

Illustration 6. Which of the following is a rigid form of matter

Ans: Ether and alcohol

Interconversion of the state of matter

Changing the temperature, pressure, or both can cause matter to change its physical condition.

a. Melting is the transformation of a solid into a liquid.

b. Solidification is the process of turning a liquid into a solid.

c. The process of converting a liquid to a gas is known as vaporisation.

d. Condensation is the process of turning a gas into a liquid.

e. Sublimation is the process of converting a solid to a gas.

Note: While increasing pressure in gas will not change the physical condition of the gas, it will bring the particles closer together, causing the gas to liquefy.

Vaporization is promoted by lowering pressure over a liquid's surface.

Illustration 7. When solid carbon dioxide is exposed to air, which of the following factors is responsible for the change in state?

a. Increase in pressure

b. Decrease in pressure

c. Increase in temperature

d. Decrease in temperature

Ans: $(a)$ Decrease in pressure; Increase in temperature

Effect of change of Temperature and Pressure 

We can change the physical condition of matter in two ways: 

a. by changing the temperature; and 

b. by changing the pressure

A solid can be changed to a liquid state by raising the temperature, and a liquid may be converted to a gaseous state by lowering the temperature.

Melting (Fusion) 

Melting is the transformation of a solid substance into a liquid when it is heated (or fusion).

Melting of the substance refers to the temperature at which a solid melts and transforms into a liquid at atmospheric pressure.

The heat energy in a solid substance causes its particles to vibrate more vigorously. At the melting point, a solid's particles have enough kinetic energy to overcome the strong forces of attraction that keep them in fixed places, and they break apart into small groups. And the solid transforms into a liquid.

The greater the force of attraction between the particles of a solid substance, the higher its melting point. The melting point of iron metal, for example, is extremely high (1535 degrees celsius), indicating that the force of attraction between the particles of iron is extremely strong.

Boiling (Vaporisation) 

Boiling is the transformation of a liquid substance into a gas when heated rapidly.

The boiling point of a liquid is the temperature at which it boils and transforms rapidly into a gas at atmospheric pressure.

Condensation 

When a gas (or vapour) is cooled sufficiently, the process of turning it into a liquid is termed condensation.

Condensation of steam occurs when steam (or water vapour) cools and converts to water (or condensation of water vapour).

It's the polar opposite of vaporisation. (Boiling)

Freezing 

Freezing is the process of turning a liquid (solidification) into a solid by chilling it, the reverse of melting. 

When a liquid cools, its particles lose energy, slowing its movement.

If the liquid is sufficiently chilled (to the point of freezing), each particle ceases to move and vibrates in a fixed location. The liquid freezes and solidifies at this point. 

As a result of the preceding discussion, we can conclude that changing the temperature can change the state of matter.

Effect of the change in Pressure on the state of matter 

Short particles separated by small distances make up matter.

Interparticle distances are exceedingly short in the solid-state.

The inter-particle distances in liquids are slightly greater than in solids.

When compared to liquids or solids, interparticle distances are greatest in the gaseous state.

As a result, it can be shown that when pressure is applied to matter, the effect on solids is insignificant because the particles are so close together.

In liquids, the effect of pressure will be minimal.

Because the interparticle distances are vast, the effect of pressure on gases will be the greatest.

As a result, when pressure is applied to gases, the particles begin to move closer together. The attractive forces between the particles increase as the particles get closer together.

This rise in attracting forces aids the gas's transition of state. When enough pressure is applied, the attraction forces build to the point where the physical state transforms from gaseous to liquid.

The reverse can be expected to happen if the pressure on a gas is decreased.

Illustration 8. Define melting process

Ans: Melting is the transformation of a solid substance into a liquid when it is heated.

Latent Heat 

The heat that a substance needs to change its condition without increasing its temperature. It's called latent heat (hidden heat) because it's buried in the substance undergoing a state transition and doesn't show up as a rise in temperature.

 “During a transition of state, the latent heat is used up in overcoming the force of attraction between the particles of the substance. It has no effect on the kinetic energy of the substance's particles. And since the substance's temperature does not rise.”

Illustration 9. What is the latent heat of fusion of ice?

Ans: $3.34\times {{10}^{5}}j/kg$ 

Latent heat of Vaporization and Fusion 

There are two types of latent heat: 

i. Latent heat of fusion 

ii. Latent heat of vaporization 

Latent heat of Vaporization

The latent heat of vaporisation is the amount of heat in Joules necessary to turn a unit quantity of 1 kg liquid into vapours without a temperature change.

Experiments have shown that it takes \[22.5\text{ }\times \text{ }{{10}^{5}}\] joules of heat to convert 1 kilogramme of water (at its boiling point, \[\text{100 }\!\!{}^\circ\!\!\text{ C}\]) to steam at the same temperature. As a result, water's latent heat of vaporisation is \[22.5\text{ }\times \text{ }{{10}^{5}}\] joules per kilogramme (or \[22.5\text{ }\times \text{ }{{10}^{5}}\]J/kg).

“If the liquid freezes to create a solid and steam condenses to form water, the substance will emit an equal amount of latent heat of fusion and vaporisation.”

The Latent Heat of Vaporization varies depending on the substance.

Latent heat of Fusion (Solid to Liquid) 

It is the amount of heat in Joules required to transform one kilogramme of solid into liquid form without causing a temperature increase.

Experiments have shown that to turn 1 kilogramme of ice into water at the same temperature (\[\text{0 }\!\!{}^\circ\!\!\text{ C}\]), \[3.34\times {{10}^{5}}\] J of heat is required.

So, latent heat of fusion of ice is \[3.34\times {{10}^{5}}\] J/ Kg. 

Different substances have different Latent Heat of Fusion.

Illustration 10. Why the temperature of melting ice does not rise even though heat is being supplied continuously.

Ans: Because ice is solid, its particles are attracted to one another by strong forces. These attraction forces keep the particles tightly packed in solid ice. The heat we give ice during melting is completely consumed by overcoming the forces of attraction between ice particles, causing them to loosen up and become liquid water. As a result of this heat not increasing the kinetic energy of particles, no temperature rise occurs during the melting of ice. However, once all of the ice has melted to create water, additional heating increases the kinetic energy of water particles, causing the temperature of the water to rapidly rise.

Sublimation

Sublimation is defined as the transformation of a solid into vapours on heating and back to a solid on cooling.

$\text{Solid}\rightleftarrows \text{Vapour (or Gas)}$ 

Ammonium chloride, iodine, camphor, naphthalene, and anthracene are some of the common substances that sublimate.

Solid carbon dioxide is yet another example of sublimation (which is commonly known as dry ice).

Carbon dioxide gas is formed when solid carbon dioxide (or dry ice) sublimates.

Illustration 11. 

a. When heated, which of the following substances sublimates:

iv. Camphor

v. Sodium Chloride

b. What happens to the heat energy that has been delivered once a solid has melted? 

c. A substance's melting point is lower than room temperature. Predict the state of its physical state. 

d. Is it permissible to refer to ammonia in its gaseous state as vapours?

e. What is the name of the chemical reaction that converts a solid into a gas?

f. During a substance's change of state, which of the following energy is absorbed?

i. Specific Heat

ii. Latent heat

iii. Heat of solution

g. Identify one common chemical that can change state when heated or cooled.

a. Camphor and iodine 

b. It is converted into latent heat of fusion 

c. It is a liquid. 

d. No, it is not 

e. It is called sublimation 

e. Latent heat 

Evaporation

The phenomenon of evaporation occurs when a liquid transforms to a gaseous state below its boiling point.

Water molecules are attracted to other water molecules in all directions, but the water molecules near the surface of the water are only dragged inward, which is below the water's surface.

Note: Evaporation is a phenomenon that occurs in all liquids in theory. But, in general, when we talk about evaporation, we're talking about water evaporation.

Vapour is a substance that can remain in a gaseous state at a temperature where it would ordinarily be a solid or liquid.

Examples of solids that can exist as a vapour: camphor, naphthalene 

Factors Affecting Evaporation 

Evaporation depends on temperature, surface area and weather conditions 

a. As the quantity of water molecules at the surface grows, evaporation increases if the surface area of the water is big. As a result, more water molecules are likely to break out once they have enough kinetic energy.

b. As the temperature approaches the boiling point of water, evaporation increases. The kinetic energy of the molecules increases as the temperature rises. The extra kinetic energy required by surface molecules to break loose or evaporate is reduced as a result. As a result, evaporation increases.

c. Evaporation decreases in excessively humid weather because the air is saturated with water molecules.

d. As water evaporates, the air just above the water surface becomes saturated with water molecules.

Illustration 12. What effect does temperature and surface area have on evaporation?

Ans: Evaporation increases as the temperature and surface area increase.

Cooling Effect 

How Does Evaporation Cause Cooling? 

When a liquid evaporates, the energy is extracted from the liquid. As a result, it continues to cool. The liquid absorbs the energy lost by the surroundings, causing them to cool. During the summer, for example, air coolers are used to provide forced cooling.

Illustration 13. Make a note of the cooling mechanism.

Ans: As a gas particle's energy drops due to cooling, the particle's moment slows down. The particles also become significantly closer to one another, resulting in the intermolecular attraction force. The gas contracts as a result of this.

Matter in our Surroundings Notes Free PDF Download

Class 9 Science Notes Chapter 1 PDF material is entirely free and can be easily availed from Vedantu’s website or application. So download the same and make it a revision guide for both unit test and final examinations. By downloading the Chapter 1 Science Class 9 Notes, you no longer need to prepare a list of essential topics and explanations by yourself. Besides the usage of simple and lucid language, this material is also drafted as per the latest CBSE curriculum, which makes it a perfect revision guide.

Class 9 Chapter 1 Science Notes – Summary

The notes of Ch 1 Science Class 9 begins with the introduction about the matter in our surroundings, its composition, what are they made up of, etc. Although you have learnt this in your previous classes, you must study it again to have a proper grasp over this concept. The next part of Class 9 Science Chapter 1 Notes explain the properties of matter. As you all know that matter is made up of tiny particles, and have unique characteristics. Additionally, these characteristics of matter are provided by a theory termed as Kinetic Theory of Matter which states the following:

Particles of matter have space between them.

Particles of matter are continuously moving – rotational and vibrational motion.

Particles of matter attract each other.

In the next section of Science Class 9 Chapter 1 Notes, students will get to know about diffusion; especially the provided diagram makes it easy to comprehend. You will also learn that diffusion occurs at a fast rate in gases. The reason for this is elaborated with suitable examples in the PDF material of Matter in our Surroundings Class 9 Notes. Besides, diffusion in liquids and solids are also discussed precisely that will help you to understand this concept clearly.

Information about the three states of matter – solid, liquid and gas are correctly laid out in this Class 9 Matter in our Surroundings Notes PDF alongside their various properties. Plus a tabular representation of differences between solid, liquid and gases is also given.

Inter Conversion of the States of Matter

With a change in pressure and temperature, matter can change from one form to another form. This section of Class 9 Science Ch 1 Notes deal regarding the same. You will get to know about all the various changes of states like melting, solidification, vaporisation, condensation, sublimation, etc in the Matter in our Surroundings Class 9 Notes.

Latent Heat and Latent Heat of Vaporisation and Fusion

This section of Class 9 th Science Chapter 1 Notes discuss latent heat and different types of the same – latent heat of fusion and latent heat of vaporisation. The different values of latent heat are also given which you can learn in the Matter in our Surroundings Class 9 Notes to write accurate answers.

Sublimation, Evaporation and Cooling Effect

In the last section of Science Chapter 1 Class 9 Notes, you will get an insight about sublimation, evaporation and cooling effect. All these state change processes are supported with appropriate examples.

Make sure to download notes of Science Class 9 Chapter 1 PDF file today from Vedantu’s official website or the app. Along with topic wise explanation, few questions and solutions are also provided in Class 9 Ch 1 Science Notes that will assist you during quick recapitulation before the exams.

Conclusion 

In conclusion, the Matter in Our Surroundings Class 9 Notes CBSE Science Chapter 1 provides a comprehensive understanding of the fundamental concepts related to matter. This chapter introduces students to the basic properties of matter, including its physical nature, states, and characteristics. The notes offer a concise and organised overview of the chapter, aiding students in grasping the key concepts effectively.

By studying these notes, students can gain knowledge about the different states of matter, such as solids, liquids, and gases, and the changes they undergo under various conditions. They also learn about the concept of the particle nature of matter and the behaviour of particles at the microscopic level.

FAQs on Matter in Our Surroundings Class 9 Notes CBSE Science Chapter 1 (Free PDF Download)

1. Is matter in our surroundings pure Class 9 notes?

Not all matter surrounding us exists in its pure form. The chapter discusses the difference between a substance and a mixture. A substance is present in its pure form, whereas, a mixture is a combination of two or more pure substances that can be separated into other types of matter through physical processes. For instance, seawater is a mixture of water and salt. Salt can be separated from it by the process of evaporation.

2. What are the basics of Class 9 Science, Chapter 1 - ‘Matter in Our Surroundings?’

Class 9 Science, Chapter 1 - "Matter in Our Surroundings," covers the fundamentals of Physical Chemistry. It starts with an introduction to matter and the three states of matter: solids, liquids, and gases. The chapter then dives into the process through which matter may change states. Some key ideas taught include the boiling and melting points. As the chapter progresses, the distinction between the latent heat of fusion and the latent heat of vapourization becomes obvious. The chapter concludes with a discussion of evaporation and the elements that influence it.

3. Will Revision Notes help ace Class 9 Science, Chapter 1 - ‘Matter in Our Surroundings?’

Yes, Revision Notes of Class 9 Chapter 1 are the ultimate and end saviour for before the exams. The students are required to go through other study material as well.

The first step is to properly read NCERT Class 9 Science, Chapter 1 - "Matter in Our Surroundings." Study the chapter attentively and attempt to grasp the fundamental principles. Clarify your doubts and reason through everything you encounter in the chapter to ensure a thorough comprehension of all the principles. Finally, using Vedantu's Revision notes, answer the back exercise questions. All issues should be reviewed on a regular basis. Answer a large number of previous year problems to learn this chapter and do well on the Science exam.

4. What are the best Revision Notes for Class 9 Science, Chapter 1 - ‘Matter in Our Surroundings?’

The best Revision Notes for Class 9 Science, Chapter 1 - ‘Matter in Our Surroundings,' can be accessed by visiting the page CBSE Class 9 Science Revision Notes Chapter 1 on the Vedantu website. Vedantu's Revision Notes are the most credible and productive study material from an examination viewpoint. If you study from these notes, you don't have to look for other study materials. These notes have zero errors and have been prepared by the best faculty of Chemistry teachers in India. All the important topics of this chapter are covered in simple language. These PDFs are available at free of cost on the Vedantu website and the Vedantu app.

5. Can I use these revision notes even in offline mode? 

Yes, by pre-downloading the pdf of revision notes the students can easily study the notes late on even when they are offline. 

STUDY MATERIALS FOR CLASS 9