case study class 9 chemistry chapter 1

Case Study Questions Class 9 Science Matter in our Surroundings

Case study questions class 9 science chapter 1 matter in our surroundings, cbse case study questions class 9 science – matter in our surroundings, case study 1:, case study 2:, case study 3:, case study 4:, case study 5:.

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

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

Last Updated on May 12, 2024 by XAM CONTENT

Hello students, we are providing case study questions for class 9 science. Case study questions are the new question format that is introduced in CBSE board. The resources for case study questions are very less. So, to help students we have created chapterwise case study questions for class 9 science. In this article, you will find case study questions for cbse class 9 science chapter 1 Matter in Our Surroundings.

Table of Contents

Case Study Questions on Matter in Our Surroundings

Question 1:

The word ‘matter’ refers to everything in the universe that has mass and takes up space. States of matter are generally described on the basis of qualities that can be seen or felt. Three states of matter can be found in daily life: solid, liquid and gas.

Matter that feels hard and maintains a fixed shape is called a solid, matter that feels wet and maintains its volume but not its shape is called a liquid. Matter that can change both shape and volume is called a gas.

Read the given passage carefully and give the answer of the following questions:

Q 1. In which form, do the water molecules have less kinetic energy?

d. All of them have equal kinetic energy

Q2. Which of the following describes the liquid phase?

a. It has a definite shape and a definite volume.

b. It has a definite shape but not definite volume.

c. It has a definite volume but not a definite shape.

d. It has neither a definite shape nor a definite volume.

Q 3. Which one of the following statements is wrong for gases?

a. Gases do not have a definite shape and volume.

b. Volume of the gas is equal to the volume of the container confining the gas.

c. Confined gas exerts uniform pressure on the walls of container in all directions.

d. Mass of the gas cannot be determined by weighing a container in which it is enclosed.

Q 4. ‘Gases are easily compressed but liquids cannot be compressed.’ What can be inferred from this statement?

a. The forces of attraction between gas particles are stronger than that between liquid particles.

b. The gas particles are spaced further apart than liquid particles. c. The gas particles have less energy than liquid particles.

d. The gas particles move more rapidly than liquid particles.

Q 5. As the solid melts to form liquid:

a. interparticle forces of attraction decrease

b. the kinetic energy of particles increases

c. compressibility increases

d. All of the above

Ice (solid) has less kinetic energy as compared to water (liquid) and steam (gas).

2. (c) It has a definite volume but not a definite shape.

3. (d) Mass of the gas cannot be determined by weighing a container in which it is enclosed.

The mass of a gas can be determined by weighing the empty container first, then filling it with gas and again weighing the container filled with gas. The difference of two readings gives the mass of gas.

4. (b) The gas particles are spaced further apart than liquid particles.

The large space between the particles of gas allow the gas to be easily compressed when pressure is applied.

5. (d) All of the above

When a solid is heated, the interparticle force decreases and kinetic energy of the particles increases. Compressibility of liquids is slightly more than solids, hence increase

Topics from which case study questions may be asked

• Matter and its physical properties
• Characteristics pf particles of mattter
• States of Matter
• Scales of Measuring Temperature
• Evaporation
• Factors affecting Rate of Evaporation

This chapter deals with the basic understanding of acids, bases, and salts, including their properties, reactions, pH scale, indicators, and practical applications.

Frequently Asked Questions (FAQs) on Matter in Our Surroundings Case Study Questions

Q1: what are case study questions for cbse examinations.

A1: Case study questions in CBSE examinations typically involve scenarios or real-life examples, requiring students to apply their understanding of concepts to solve problems or analyze situations.

Q2: Why are case study questions important for understanding class 9 science chapters?

A2: Case study questions provide a practical context for students to apply theoretical knowledge to real-world situations, fostering deeper understanding and critical thinking skills.

Q3: How should students approach answering case study questions for CBSE?

A3: Students should carefully read the case study, identify the key issues or problems presented, analyze the information provided, apply relevant concepts and principles of chemical reactions and equations, and formulate well-supported solutions or responses.

Q4: Are there any resources available online for students to practice case study questions on class 9 science chapters for CBSE exams?

A4: Yes, several educational websites offer case study questions for CBSE students preparing for science examinations. We also offer a collection of case study questions for all classes and subject on our website. Visit our website to access these questions and enhance your learning experience. If you need more case study questions for your preparation, then you visit Physics Gurukul website.

Q5: How can students effectively prepare for case study questions on chemical reactions and equations for CBSE exams?

A5: Effective preparation strategies include regular revision of concepts, solving practice questions, analyzing case studies from previous exams, seeking clarification on doubts, and consulting with teachers or peers for guidance and support.

Q6: How can teachers incorporate case study questions on matter in our surroundings class 9 science into classroom teaching?

A6: Teachers can integrate case studies into lesson plans, group discussions, or interactive activities to engage students in active learning, promote problem-solving skills, and facilitate a deeper understanding of acids, bases and salts.

Q7: What is matter made up of?

A7: Matter is made up of particles.

Q8: What happens when salt is added to water?

A8: When we add salt in water, the particles of salt get into the spaces between particles of water. We say that salt has been dissolved into water.

Q9: What happens when we light the incense stick in one corner of a room?

A9: The smell of the incense stick spreads throughout the room due to diffusion

Q10: Which of the following substances diffuses faster in a glass of water: a drop of honey or blue ink?

A10: Blue ink, because of the high kinetic energy of the particles of the given matter. Honey is viscous, and has low kinetic energy.

Q11: Why does diffusion becomes faster on heating?

A11: On heating, the kinetic energy of the particles increases and the particles move faster. This speeds up the intermixing of particles

Q12: Why do the gases exert more pressure on the walls of the container than the solids?

A12: In gases, the particles move randomly at high speed and they collide with each other and with walls of the container. Due to this collision with walls of the container, the gases exert more pressure than solids.

Q13: What happens to the particles of the solid during sublimation?

A13: Sublimation is a process in which the solid changes directly to gas either by decreasing pressure or increasing temperature. A decrease in pressure increases the space between the particles and an increase in temperature increase the kinetic energy of the particles.

Q14: List all the factors which affects the rate of evaporation.

A14: The factors affecting the rate of evaporation are: (a) an increase in surface area (b) an increase in temperature (c) an increase in wind speed (d) a decrease in humidity

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Class 9 Science Case Study Questions

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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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RD Sharma Solutions , RS Aggarwal Solutions and NCERT Solutions

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

November 15, 2023 by Prasanna

These Solutions are part of NCERT Solutions for Class 9 Science . Here we have given NCERT Solutions for Class 9 Science Chapter 1 Matter in Our Surroundings. LearnInsta.com provides you the Free PDF download of NCERT Solutions for Class 9 Science (Chemistry) Chapter 1 – Matter in Our Surroundings solved by Expert Teachers as per NCERT (CBSE) Book guidelines. All Chapter 1 – Matter in Our Surroundings Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks.

More Resources

• NCERT Solutions for Class 9 Science
• HOTS Questions for Class 9 Science
• Value Based Questions in Science for Class 9
• NCERT Exemplar Solutions for Class 9 Science
• Previous Year Question Papers for CBSE Class 9 Science

NCERT IN TEXT PROBLEMS

IN TEXT 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, smell, almonds, cold drink, smell of perfume are matter. Please note that the smell whether pleasant or foul is due to the presence of some particles in air. It is therefore, a matter. Love, hate, thought and cold are simply feeling. They do not represent matter.

Question 2. The smell of hot sizzling food reaches us several metres away. However, it is not so in case the food is cold. Explain. Answer: When food is sizzling hot, it releases the vapours of its contents. Since the kinetic energy of the particles is very high in the vapour state, these particles readily mix up with the particles of air. They can reach us even at a distance of several metres. However, when the food is cold, the vapours released will be comparatively less. Moreover, their kinetic energy is also very small. Under these conditions, one has to come quite close in order to smell the contents of the food.

Question 3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show ? (CBSE 2013) Answer: The observation explains the following properties of water (liquid state of matter) or any other liquid.

• The inter particle forces of attraction are not very strong in water.
• The inter particle spaces are somewhat large in water.
• All these properties associated with the liquid state or water enable the diver to cut through water in a swimming pool.

Question 4. What are the characteristics of the particles of matter ? Answer: Characteristics of the Particles of Matter We have studied that matter is composed by particles and there are interparticle spaces as well. Let us brief by study the main characteristics of these particles supported by some activities.

• Particle Size is Extremely Small
• Particles are in a State of Motion
• Inter Particle Attractions Keep Particles Close
• Effect of Temperature on Particle Motion

Question 5. The mass per unit volume of a substance is known as density (density = mass/volume). Arrange the following in order of increasing density : Air, exhaust from chimneys, honey, water, chalk, cotton and iron. Answer: The increasing order of density for the given substances is : Air, exhaust from chimneys, cotton, water, honey, chalk, iron. Actually, the density of a substance depends upon the number of particles per unit volume as well as upon their mass. The number of the particles is related to their size as well as the attractive forces among them. Keeping this in view, the increasing order of density is as given above.

Question 7. Comment on the following : rigidity, compressibility, fluidity, filling of a gas in cylinder, shape, kinetic enegy and density. Answer: Rigidity: Solids are known for their hardness and rigid nature. Compressibility: Actually, the constituent particles are so closely packed in a solid that they either do not come closer or do so only slightly when a high pressure is applied. However, there are some exceptions. For example, a sponge made from some foam or rubber material can be easily compressed. Fluidity: We have seen that rigidity is maximum in the solid state and fluidity or particle motion is negligible. In the liquid state of a substance, both these characters are different. The liquids are less rigid than the solids and the molecular motion is also comparatively more. Filling of a Gas in Cylinder: All of us are quite familiar with a cooking gas cylinder which contains in it liquefied petroleum gas, often called L.P.G. It is a mixture of different gases such as propane, butane etc. These are so highly compressed that they are in the liquefied form. When the regulator is opened, the liquid escapes from the nozzle of the cylinder into a space where pressure is very less. Shape: Solids generally have fixed shapes. They donot change their shapes even when put in different containers. For example, blue crystals of copper sulphate have needle like shape which they retain whether kept in a beaker or in a china dish or placed on the palm of our hand. Kinetic Enegy: The kinetic energy of the particles in the liquid state of a substance is more than in solid state. It further increases with the rise in temperature. Density: The density of the gas (mass/volume) is very small and the gases are therefore, light.

Question 8. Why does a gas fill completely the vessel in which it is kept ? Answer: This happens because of fast diffusion of the particles in a gas. The number of vacant spaces or voids in the gaseous state is very large. This means that the particles of a gas move at a very fast speed. They readily fill completely the vessel in which the gas is kept. Thus, the volume of the gas is the same as that of the vessel.

Question 9. A gas exerts pressure on the walls of the container. Assign reason. (CBSE 2012, 2013) Answer: The molecules in a gas have large kinetic energy. They strike the walls of the container with certain force and impart momentum to them. The force per unit area or momentum is responsible for the pressure of the gas.

Question 10. Why should we call a wooden table a solid ? (CBSE 2012, 2013) Answer: A wooden table should be called a solid because it matches the characteristics of the solid state. For example,

• It is very hard and rigid.
• Its shape cannot be changed by altering temperature or pressure. .
• It is quite heavy which means high density.
• There is no movement of the constituent particles present.

Question 11. We can easily move our hand in air but to do so the same through a solid block of wood, we need a ‘Karate expert’. Explain. Answer: In air, the interparticle spaces are very large in number and the interparticle forces are quite weak. These can be easily overcome. That is why our hand can move in air. These spaces help in moving our hand in air, But in a solid block, the constituent particles are quite close and the interparticle forces are very strong. In case, one has to move his hand through a solid, it will be extremely difficult. Only a karate expert may do so.

Question 12. Liquids generally have low density as compared to solids. But you must have observed that ice floats on water. Find out why ? Answer: Ice (solid state) is expected to be heavier than water (liquid state). But it is lighter and floats over water. Actually, ice has a cage like structure which means that vacant spaces are left when H 2 O molecules are linked in ice. The number of these spaces are comparatively less in water. In other words, we can also say that the structure of ice is more porous than that of water. Therefore, water is dense as compared to ice or ice floats over water.

Question 13. Convert the following temperatures to Celsius scale : (a) 300 K (b) 573 K. Answer: (a) (300 – 273) = 27°C (b) (573 – 273) = 300°C.

Question 14. What is the physical state of water at : (a) 250°C (b) 100°C ? Answer: Boiling point temperature of water is 100°C. Above this temperature (250°C), water exists in the gaseous state i.e., as vapours or as steam. However, at 100°C, both liquid and gaseous states are present. Actually, at the boiling point temperature, both the liquid and gaseous states of a substance co-exist. These are in a state of equilibrium. We may conclude that at 100°C, both liquid water and vapours are present but at 250°C we have only vapours or steam and no liquid.

Question 15. For any substance, why does the temperature remain constant during the change of state ? Answer: Once the change of state of a substance begins or starts, the energy which is now supplied is being used up as latent heat. It means that it does not increase the kinetic energy of the particles and is used up only to overcome the inter-particle forces in that particular state and to bring about a change in state. Therefore, the temperature becomes constant.

Question 16. Suggest a method to liquefy atmospheric gases. Answer: In order to liquefy a gas, the constituent particles or molecules have to be brought closer. The atmospheric gases can be liquefied either by increasing pressure or by decreasing temperature.

Question 17. A cooler is quite effective on a hot and dry day. Explain. Answer: Under the conditions, the humidity level in the atmosphere is quite low and the evaporation rate of water is expected to be high. Since cooling is caused during evaporation, the air which escapes from the cooler is compartively cold under these conditions. Therefore, is quite effective on a hot and dry day.

Question 18. How does water kept in an earthen pot become quite cold during summer ? Answer: The earthen pot is full of small pores. Water present in these pores has a tendency to escape at a fast rate during summer. The escaping molecules of water appear as water vapours and evaporate. Since cooling is caused in evaporation, the temperature of the water inside the earthen pot gets considerably lowered and it becomes cold.

Question 19. When we pour some acetone or perfume on our palm, we get a cooling sensation. Assign reason. Answer: Both acetone and perfume are low boiling liquids. When any of them is poured on the palm, it readily changes into vapours or evaporates. For this, it needs some energy which is taken from the palm. The temperature of the palm gets lowered and we get a cooling sensation.

Question 20. Why can we sip hot tea from a saucer faster than from a cup ? Answer: The phenomenon of change of liquid to the vapour state at any temperature below the boiling point of the liquid. In a liquid, the particles or molecules experience mutual forces of attraction. However, these are not stationary and have some kinetic energy at all temperatures. The particles of a liquid are also colliding with one another and exchanging energy during the collisions. Above the liquid surface, atmosphere or air is present which is a mixture of several gases. The particles of the liquid present on the surface have a tendency to come out from the surface so that they may acquire more freedom to move and become part of the atmosphere. This is also known as randomness. To overcome the interparticle forces of attraction, they need some energy which they take up from the rest of the particles or molecules of the liquid. As a result, their temperature gets lowered and cooling is caused.

NCERT END EXERCISE

Question 1. Convert the following temperatures to Celsius scale ? (a) 293 K (b) 470 K. Answer: (a) (293 – 273) = 20°C (b) (470 – 273) = 197°C

Question 2. Convert the following temperatures to Kelvin scale (a) 25°C (b) 373°C.   (CBSE 2014) Answer: (a) (25 + 273) = 298 K (b) (373 + 273)’= 646 K.

Question 3. Give reasons for the following observations : (a) Naphthalene balls disappear with time without leaving any solid (CBSE 2011, 2013) (b) We can get the smell of perfume sitting several metres away. (CBSE 2013) Answer: (a) Naphthalene has a tendency to sublime i.e. it changes directly to the gaseous state. Therefore, the size of the naphthalene balls slowly decreases and ultimately they disappear. No solid residue is left. (b) A perfume is actually a mixture of number of pleasant smelling vapours. They diffuse quite fast and can reach a person who may be even at several metres away from a person who has used perfume.

Question 4. Arrange the following substances in increasing order of attraction between the particles : water, sugar, oxygen. (CBSE 2012) Answer: The three substances differ in their physical state at normal temperature. Oxygen is a gas, water a liquid while sugar is a crystalline solid. Keeping this is mind, the increasing order of attraction between the particles is : oxygen < water < sugar.

Question 5. What is the physical state of water at (a) 25°C               (b) 0°C                (c) 100°C ? [CBSE 2014] Answer: (a) At 25°C, water is in the liquid state (b) At 0°C, water can exist both in the solid state (ice) and in liquid state. This temperature represents the melting point of ice and freezing point of water (c) At 100°C, water can be present both in the liquid and vapour states. This temperature corresponds to the boiling point of water and liquefication temperature of steam.

Question 6. Give two reasons to justify that :

• water at room temperature is a liquid
• an iron almirah is a solid at room temperature. (CBSE 2012, 2013)
• When placed in a beaker, its level cannot be changed on pressing.
• It can take the shape of any container in which it is placed.
• Its shape does not change when pressed. This means that it is hard and rigid.
• It is very heavy. This means that its density is very high.

Question 7. Ice at 273 K causes more cooling than water at the same temperature. Explain. (CBSE 2015) Answer: Ice (solid state) has extra energy in the form of latent heat of fusion (335 kj kg-1) as compared to water. When ice is to melt, it takes energy from the surroundings to overcome this latent heat. The temperature of the surroundings gets lowered or cooling is caused. Since water is already in the liquid state, it will hardly take up any energy from the surroundings.

Question 8. Why does steam produce more severe burns on the skin as compared to boiling water ? (CBSE 2015) Answer: Steam is formed when water at its boiling point temperature of 100°C (373 K) absorbs latent heat of vaporisation. Therefore, steam has more energy than boiling water. On account of this, steam produces more severe burns on the skin as compared to boiling water.

VERY SHORT ANSWER QUESTIONS

Question 1. What is common in the three states of matter ? Answer: All of them occupy space and have mass.

Question 2. Can we regard high fever as matter ? Answer: Fiigh fever is a feeling only. It cannot be regarded as matter.

Question 3. Why do not solids possess fluidity ? Answer: Fluidity means tendency to flow. The constituents in the solids are very closely packed and interparticle forces are quite strong. Therefore, solids have hardly any fluidity.

Question 4. A certain substance ‘A’ cannot be compressed but takes up the shape of any container in which it is placed. What will you regard its physical state ? Answer: The physical state of the substance ‘A’ is a liquid.

Question 5. Why do substances undergo change in physical state ? Answer: Substances undergo change in physical state because both interparticle spaces and interparticle forces can be changed by changing the conditions of temperature and pressure.

Question 6. What is the pressure at sea level ? Answer: The pressure at sea level is regarded as 1 atmosphere or 760 mm.

Question 7. Are the melting point temperature of the solid state and the freezing point temperature of the liquid state of a substance different ? Answer: No, these are the same. For example, melting point of ice and freezing point of water are both 0°C or 273 K.

Question 8. Why are gases highly compressible ? Answer: Because the interparticle empty spaces are very large. When a gas is compressed, these spaces decrease. The particles or molecules of gas come closer.

Question 9. A substance is in liquid state at room temperature and changes into gaseous state upon heating. What will you call its gaseous state ? Answer: The gaseous state of the substance is regarded as vapours.

Question 10. When a crystal of copper sulphate is placed at the bottom of a beaker containing water, the colour of water slowly becomes blue, why ? Answer: The crystal breaks into fine particles which form copper ions (Cu2+ ions) in solution. As these ions (blue in colour) spread, the colour of water slowly becomes blue.

Question 11. Why do solids generally lack the property of diffusion ? Answer: This is because of the absence of translatory motion in the solid state since the particles are very closely packed.

Question 12. Do we represent the temperature on kelvin scale by the letter ‘k’ or ‘K’ ? Answer: The temperature on Kelvin scale is represented by the letter K (capital letter).

Question 13. The boiling point of ethyl alcohol is 78°C. What is the corresponding temperature on kelvin scale ? Answer: Temperature on kelvin scale = 78 + 273 = 351 K

Question 14. When a solid starts melting, its temperature does not rise till whole of it has melted. Explain. Answer: The heat energy which is now being supplied is used up to bring a change in physical state only. It is known as latent heat of fusion.

Question 15. A substance upon heating directly changes into gaseous state. What is this change called ? Answer: It is known as sublimation.

Question 16. Define gaseous state of a substance. Answer: A substance is said to be in the gaseous state if under normal pressure, its boiling point is below the room temperature. In other words, at room temperature the substance is in the gaseous state.

Question 17. Represent freezing and boiling temperatures of water in Celsius as well as in Kelvin scales. (CBSE 2012) Answer: Freezing point temperature of water : 0°C or 273 K Boiling point temperature of water : 100°C or 373 K.

Question 18. Does the evaporation of a liquid occur only at a fixed temperature ? Answer: No, the evaporation of a liquid occurs at all temperatures.

Question 19. What is the name given to the process when the vapours of a liquid get cooled ? Answer: The process is known as condensation.

Question 20. Does the temperature of liquid increase further when it starts boiling ? Answer: No, it does not because the energy now supplied is used up as latent heat of vaporisation only.

Question 21. Why do we sweat more in a humid day ? Answer: In a humid day, the air around us has already high percentage of water vapours. Therefore, the water coming from the skin gets less opportunity to change into vapours and remains sticking to our body. We therefore, sweat more on a humid day.

Question 22. How does pressure help in the liquefication of a gas ? Answer: Increase in pressure helps in the liquefication of a gas. The particles or molecules of a gas come closer and closer as the pressure is being increased gradually. They ultimately condense and as a result, the gas liquefies or changes into the liquid state.

Question 23. What is meant by saying that latent heat of vaporisation of water to 226 kj/kg -1 . Answer: This means that when one kg of water at its boiling point temperature changes into steam, 226 kj of heat is absorbed.

Question 24. In which state of matter

• Intermolecular forces are the maximum,
• Diffusion is the least
• Intermolecular spaces are the maximum ?
• Solid state
• Gaseous state.

Question 25. Latest heat of vaporisation of two liquids A and B are 100 J/kg and 150 J/kg respectively. Which one can produce more cooling effect ? Answer: The liquid B can cause more cooling effect than the liquid A because it absorbs more heat from the surrounding during the change of state from liquid to the vapours.

Question 26. What temperature in Kelvin scale is equal to 50°C ? Answer: 50°C = 50 + 273 = 323 K.

Question 27. Why does a balloon inflate when air is blown into it ? Answer: On blowing air into a balloon, the volume of air inside increases. As a result, balloon inflates.

Question 28. Write full form of

• Compressed natural gas
• Liquid petroleum gas.

Question 29. Melting points of three solids X, Y and Z are 298K, 314K and 398K respectively. Arrange these in increasing order of inter particle forces of attraction. Answer: Please remember that greater the melting point temperature of a solid, more is the magnitude of interparticle forces. The correct is X < Y < Z.

Question 30. What happens to the heat energy supplied to a solid once it starts melting ? Answer: The heat energy is supplied as latent heat of fusion. There is no change in the temperature till the entire solid has melted. .

Question 31. You are provided with a fine white coloured powder which is either sugar or salt. How will you identify it without testing ? Answer: We can identify them by taste only. Sugar tastes sweet whereas common salt as we all know, has a bitter taste.

Question 32. Name the term used for the following : (CBSE 2014)

• Conversion of vapours to solid
• Conversion of solid to liquid
• Conversion of vapours to liquid.
• Freezing or solidification
• Condensation.

SHORT ANSWER QUESTIONS

Question 33. Assign reasons for the following : Why do wet clothes do not dry easily on a rainy day. (CBSE 2016) Answer: In a rainy day, the humidity level in the atmosphere is already high. As a result, it will be quite difficult for the moisture associated with wet clothes to change into vapours. Therefore, they will remain wet.

Question 34. Why are gases highly compressible while solids are almost incompressible ? Answer: In the gases, the inter particle or inter molecular spaces are very large. These can be decreased to a large extent on applying pressure. Therefore, the gases are highly compressible, very small and cannot be decreased any more on applying pressure, incompressible.

Question 35. Arrange in the order indicated for solid, liquid and gas.

• effect of pressure – increasing order
• empty spaces in the particles – decreasing order
• tendency to flow – decreasing order
• thermal expansion – increasing order.
• solid, liquid, gas
• gas, liquid, solid
• solid, liquid, gas.

Question 36. Name the state of matter that

• has definite mass, volume and shape
• has no definite volume and shape
• has minimum inter particle attraction
• has maximum inter particle attraction.
• solid state
• gaseous state

Question 37. (a) Butter is generally wrapped in wet cloth during summer if no refrigerator is available. Explain. (CBSE 2015) (b) The Latent heat of vaporisation of steam is more than that of the boiling water. Explain. Answer: (a) In summer, the weather is a quite hot. As a result, water present in wet cloth readily evaporates. Since cooling is caused during evaporation, the temperature of butter gets lowered. This checks the rancidity of butter or it does not give any foul odour. (b) When boiling water changes into steam, it absorbs a certain amount of heat energy. This shows that the latent heat of vaporisation of steam is more than that of boiling water.

Question 38. Which of the following factor(s) is (are) responsible for the change of state of solid carbon dioxide into vapours ? (a) Increase in pressure (b) Decrease in presssure (c) Increase in temperature (d) Decrease in temperature. Answer: The change of state can take place by decreasing the pressure and increasing the temperature.

Question 39. How will you justify that ice, water and steam are not different substances but different states of the same substance ? Answer: When ice (solid state) is heated, it melts and changes to water (liquid state). When water is boiled, it is converted to steam (gaseous state). The process can be reversed upon cooling. This justifies that these are the states of a substance. In fact all the three states are chemically the same with the formula H 2 O.

Question 40. Name the process associated with the following : (a) Dry ice is kept at room temperature and under one atmosphere pressure. (b) A drop of ink placed on the surface of water contained in a glass spreads throughout water. (c) A crystal of potassium permanganate is put in water contained in a beaker and stirred with a glass rod. (d) Milk is churned to seperate cream from it. (e) Settling of sand when a mixture of sand and water is left undisturbed for sometime. Answer: (a) Sublimation (b) Diffusion (c) Dissolution/diffusion (d) Centrifugation (e) Sedimentation.

Question 41. (a) Solids are generally very heavy while gases are light. Explain. (b) Carbon dioxide gas is heavier than both nitrogen and oxygen. Why does not it form lower layer in the atmosphere ? Answer: (a) In the solids, the particles are very closely packed. As a result, the number of particles per unit volume is quite large. Therefore, the solids are normally quite heavy. In the gases, the particles are loosly packed. The number of particles per unit volume is comparatively small. Therefore, gases are light. (b) The diffusion of a gas is not affected by gravity. This means that carbon dioxide (CO 2 ) remains uniformly mixed in air. Therefore, the gas does not form the lower layer in the atmosphere.

Question 42. How do surface area and wind speed affect rate of evaporation ? (CBSE 2014) Answer: With increase in surface area, more molecules of the liquid get opportunity to come to the surface and change into vapours. Similarly, with the increase in wind speed, the particles of water vapours present in air move away and the air which replaces it is comparitively dry. This will increase the rate of evaporation.

Question 43. (a) Explain why there is no rise in temperature of a substance when it undergoes a change of state although it is still being heated. (b) Name one property which is shown by naphthalene and not by sodium chloride. Answer: (a) Once the change in state of a substance starts (solid to liquid or liquid to gas), the temperature of the substance does not change. Actually, the heat energy now supplied does not increase the kinetic energy of the constituting particles. It is absorbed either as latent heat of fusion or as latent heat of vaporisation. (b) Naphthalene undergoes sublimation upon standing/heating and directly changes into vapours. Sodium chloride (common salt) does not undergo sublimation. It melts on strong heating.

Question 44. The molecules of water have more energy as compared to molecules of ice at same temperature. Justify this statement. Answer: When ice is to melt, energy is absorbed to overcome intermolecular forces of attraction. Since the intermolecular forces of attraction decrease, the kinetic energy of molecules in water is more than in ice.

Question 45. Define (a) Latest heat of fusion,  (b) Melting point   (c) Fusion. Answer: (a) Latent heat of fusion : It is the amount of heat energy which is needed to convert one kg of a solid into the liquid state at its melting point temperature without any rise in temperature under one atmosphere pressure. (b) Melting point : It is the tempetature at which a solid starts melting or starts changing into the liquid state. (c) Fusion : The process of the change of the solid state into the liquid state is known as fusion.

Question 46. Give reasons for the following : (a) A liquid generally flows easily. (b) Ice at 0°C appears colder in the mouth than water at 0°C. (c) Doctors advise to put strips of wet cloth on the forehead of a person having high fever. Answer: (a) The intermolecular forces in a liquid are weak. Its molecules are able to slide over one another and liquid generally flows easily. (b) Latent heat of fusion of ice is quite high. In the mouth, ice absorbs this heat and melts. That is why ice at 0°C gives more cooling sensation in the mouth than water at the same temperature. (c) As water evaporates from the strips of wet cloth placed on the forehead of a person, it absorbs heat from the body. The body temperature gets lowered and the person gets some relief from fever.

Question 47. Prachi took 50 mL of water in two beakers at room temperature and added sodium chloride to one beaker while sugar to the other, till no more solute would dissolve. Then she heated the contents of the beakers and added more solutes in them. (a) Will the amount of salt and sugar that can be dissolved in water at given temperature same ? (b) What will you expect to happen if she cools the contents of the beakers ? Justify your answer. Answer: (a) No, they will be different. Actually sodium chloride (salt) is a crystalline solid while sugar is a molecular solid. They dissolve to different extent. Sodium chloride is more soluble in water compared, to sugar at a given temperature, (b) Upon cooling, solid solute will slowly start separating from the solution. In general, the solubility of a solid in a liquid increases with the rise in temperature and decreases as the temperature is lowered.

Question 48. Explain the interconversion of three states of matter in terms of force of attraction and kinetic energy of the molecules. Answer: The intermolecular force of attraction is maximum in the solid state and minimum in the gaseous state. Similarly, the kinetic energy of the molecules is minimum in the solid state and maximum in the gaseous state. The change of state can be brought about by either changing the temperature or pressure.

Question 49. Carbon dioxide was taken in an enclosed cylinder and compressed by applying pressure (a) Which state of matter will we obtain after completion of the process ? (b) Name and define this process. (c) What is the common name of the product obtained in the above process ? Answer: (a) Liquid state of matter will be obtained, (b) The process is known as liqueficadon. It is the change of state from gas to the liquid by increasing pressure or decreasing temperature, (c) It is known as liquid CO 2 .

LONG ANSWER QUESTIONS

Question 50. (a) What is the reason for the existence of the three states of matter ? (b) What will happen when solid ammonium chloride is heated ? (c) The room temperature is 25°C. What is the corresponding temperature on the Kelvin scale ? (d) What happens to the particle motion if the temperature of the gas is increased ? (e) A substance ‘X’ was highly compressible and could be easily liquified. It could also take up the shape of any container. Predict the nature of the substance. Enlist four properties of this state of matter. Answer: (a) The three states of matter differ with respect to the inter particles spaces. These are minimum in the solid state while maximum in the gaseous state, (b) It will directly change to the vapour state without passing through the liquid state. The process is known as sublimation. (c) Kelvin temperature (K) = 273 + 25 = 298 K. (d) With the increase in temperature, the average kinetic energy of the particles increases. As a result, the particle motion increases. (e) The substance ‘X’ appears to be a gas since the characteristics shown by it resemble those of the gaseous state. For the properties of the gaseous state.

Question 52. Define melting point of a solid. At what temperature on the Kelvin scale does ice melt ? In the experiment to determine the melting point of ice, why does the temperature not rise till all the ice has melted even though heat is supplied continuously ? What is this heat energy called ? Answer: As long as ice has not melted, the heat energy supplied increases the kinetic energy of particles (or H2O molecules) which constitute ice. As a result, the temperature rises. Once the process of melting of ice starts, the heat energy is now consumed in bringing about the change in state from solid to liquid. We can also say that the heat energy is used up to overcome the intermolecular forces of attraction present among the H 2 0 molecules in ice. Thus, it is absorbed by ice without changing the temperature. This is known as latent heat which means that it is in hidden form as it is not visible. (In Greek : latent means-hidden) In case of solids, it is known as latent heat of fusion (fusion means melting). It may be defined as : The amount of heat energy that is needed to convert one kg of a solid into the liquid state at its melting point temperature without any rise in temperature under atmospheric (one atmosphere) pressure.

Question 54. Account for the following : (a) The temperature of water remains constant during boiling. (b) Evaporation is a surface phenomenon. (c) The spaces between constituent particles is maximum in the gaseous state. Answer: (a) Once a liquid starts boiling, there is no increase in average kinetic energy upon further heating. The heat now supplied is used to overcome intermolecular forces only. Therefore, the temperature of water remains constant during boiling. (b) Molecules or particles of a liquid present on the surface have an urge or desire to escape from the surface as vapours in order to increase their free movement or randomness. This is known as evaporation. Thus, evaporation is a surface phenomenon. More the surface area available more will be the rate of evaporation. (c) In the gaseous state of matter the interparticle forces are the least. Therefore, interparticle spaces are the maximum.

Get 100 percent accurate NCERT Solutions for Class 9 Science Chapter 1 (Matter in Our Surroundings) explained by expert Science teachers. We provide solutions for the questions given in Class 9 Science textbook as per CBSE Board guidelines from the latest NCERT book for Class 9 Science. The topics and sub-topics in  Chapter 1 Matter in Our Surroundings

• 1.1 Physical Nature of Matter
• 1.1.1 MATTER IS MADE UP OF PARTICLES
• 1.1.2 HOW SMALL ARE THESE PARTICLES OF MATTER?
• 1.2 Characteristics of Particles of Matter
• 1.2.1 PARTICLES OF MATTER HAVE SPACE BETWEEN THEM
• 1.2.2 PARTICLES OF MATTER ARE CONTINUOUSLY MOVING
• 1.2.3 PARTICLES OF MATTER ATTRACT EACH OTHER
• 1.3 States of Matter
• 1.3.1 THE SOLID STATE
• 1.3.2 THE LIQUID STATE
• 1.3.3 THE GASEOUS STATE
• 1.4 Can Matter Change its State?
• 1.4.1 EFFECT OF CHANGE OF TEMPERATURE
• 1.4.2 EFFECT OF CHANGE OF PRESSURE
• 1.5 Evaporation
• 1.5.1 FACTORS AFFECTING EVAPORATION
• 1.5.2 HOW DOES EVAPORATION CAUSE COOLING?.

We cover all exercises in the chapter given below:-

• EXERCISE 1.1 – 4 Questions with Solutions
• EXERCISE 1.2 – 4 Questions with Solutions
• EXERCISE 1.3 – 4 Questions with Solutions
• EXERCISE 1.4 – 5 Questions with Solutions
• EXERCISE 1.5 – 9 Questions with Solutions.

Download the free PDF of Chapter 1 Matter in Our Surroundings or save the solution images and take the print out to keep it handy for your exam preparation.

Hope given NCERT Solutions for Class 9 Science Chapter 1 are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Class 9 Science Case Study Questions PDF Download

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Class 9 Science Case Study Questions play a crucial role in the field of science education as they provide real-life scenarios for students to analyze, apply their knowledge, and develop problem-solving skills. This article aims to present a comprehensive collection of case study questions for Class 9 Science , covering various topics and concepts.

Join our Telegram Channel, there you will get various e-books for CBSE 2024 Boards exams for Class 9th, 10th, 11th, and 12th.

CBSE Class 9 Science Exam will have a set of questions based on case studies in the form of MCQs. The CBSE Class 9 Science Question Bank on Case Studies, provided in this article, can be very helpful to understand the new format of questions. Share this link with your friends.

If you want to want to prepare all the tough, tricky & difficult questions for your upcoming exams, this is where you should hang out.  CBSE Case Study Questions for Class 9  will provide you with detailed, latest, comprehensive & confidence-inspiring solutions to the maximum number of Case Study Questions covering all the topics from your  NCERT Text Books !

Table of Contents

CBSE Class 9th SCIENCE Chapterwise Case Study Question & Solution

Case study questions provide students with real-life scenarios that require critical thinking and application of scientific concepts. They help students understand the practical application of scientific principles and develop problem-solving skills in various scientific disciplines.

Chapterwise Case Study Questions for Class 9 Science

Inboard exams, students will find the questions based on assertion and reasoning. Also, there will be a few questions based on case studies. In that, a paragraph will be given, and then the MCQ questions based on it will be asked. For Science subjects, there would be 5 case-based sub-part questions, wherein a student has to attempt 4 sub-part questions.

• Case Study Questions for Chapter 1 Matter in Our Surroundings
• Case Study Questions for Chapter 2 Is Matter Around Us Pure?
• Case Study Questions for Chapter 3 Atoms and Molecules
• Case Study Questions for Chapter 4 Structure of Atom
• Case Study Questions for Chapter 5 The Fundamental Unit of Life
• Case Study Questions for Chapter 6 Tissues
• Case Study Questions for Chapter 7 Diversity in Living Organisms
• Case Study Questions for Chapter 8 Motion
• Case Study Questions for Chapter 9 Force and Laws of Motion
• Case Study Questions for Chapter 10 Gravitation
• Case Study Questions for Chapter 11 Work and Energy
• Case Study Questions for Chapter 12 Sound
• Case Study Questions for Chapter 13 Why do we Fall ill
• Case Study Questions for Chapter 14 Natural Resources
• Case Study Questions for Chapter 15 Improvement in Food Resources

The above  Case studies for Class 9 Science  will help you to boost your scores as Case Study questions have been coming in your examinations. These CBSE Class 9 Science Case Studies have been developed by experienced teachers of schools.studyrate.in for the benefit of Class 10 students.

Class 9 Maths Case Study Questions

Benefits of Case Studies in Science Education

Case studies offer several advantages over traditional teaching methods. Here are some key benefits:

• Real-World Application : Case studies present authentic scenarios, enabling students to understand how scientific concepts are applied in real-life situations.
• Critical Thinking : Analyzing case studies requires students to think critically, make connections, and apply scientific knowledge to solve problems.
• Interdisciplinary Approach : Case studies often involve multiple scientific disciplines, fostering an interdisciplinary understanding of complex issues.
• Engagement and Active Learning : Case studies actively engage students in the learning process, promoting active participation, discussion, and collaboration.
• Skill Development : Case studies develop essential skills such as analytical thinking, problem-solving, and effective communication of scientific concepts.

Importance of Practicing Case Study Questions

Practicing case study questions is crucial for Class 9 Science students to enhance their understanding and application of scientific concepts. Here’s why it is important:

• Application of Knowledge : Case studies allow students to apply their theoretical knowledge to practical situations, bridging the gap between theory and real-world scenarios.
• Developing Analytical Skills : Analyzing case studies improves students’ ability to identify relevant information, make connections, and draw logical conclusions.
• Problem-Solving Skills : Case studies present complex problems that require students to think critically and develop effective problem-solving strategies.
• Enhanced Exam Performance : Practicing case study questions familiarizes students with the format and types of questions they may encounter in exams, leading to improved performance.

Subjects Covered in the Case Study Questions for Class 9 Science

The case study questions for Class 9 Science cover the following subjects:

• Motion and Forces
• Light and Reflection
• Electricity
• Matter and Its Properties
• Atoms and Molecules
• Structure of the Atom
• Chemical Reactions
• Cell: The Fundamental Unit of Life
• Diversity in Living Organisms
• Natural Resources

Tips for Approaching Case Study Questions

To tackle case study questions effectively, consider the following tips:

• Read Carefully : Pay close attention to the details provided in the case study, as they hold crucial information for solving the problem.
• Analyze Methodically : Break down the problem into smaller components and analyze each part systematically.
• Apply Relevant Concepts : Identify the scientific principles relevant to the case study and apply them appropriately.
• Consider Multiple Perspectives : Explore different angles and viewpoints while proposing solutions, taking into account various scientific factors.
• Provide Justifications : Support your answers with scientific explanations and logical reasoning to strengthen your responses.

The Class 9 Science Case Study Questions provided in this article serve as a valuable resource for students seeking to enhance their scientific knowledge and problem-solving skills. By practicing these case studies, students can develop a deeper understanding of scientific concepts and their practical applications. Embrace this opportunity to engage with real-world scenarios and strengthen your scientific acumen.

Q1: Are the Class 9 Science Case Study Questions aligned with the official curriculum?

Yes, the Class 9 Science Case Study Questions presented in this article are aligned with the official curriculum. They cover relevant topics and concepts that students need to study for their exams.

Q2: Can practicing case study questions alone guarantee success in Class 9 Science exams?

Practicing case study questions is an important part of exam preparation, but it should be complemented with a thorough understanding of the subject matter. It is advisable to study the concepts in detail, refer to textbooks, and engage in other learning activities to achieve success in exams.

Q3: Where I Can get Class 9 Science Case Study Questions ?

You can practice Class 9 Science Case Study Questions on schools.studyrate.in for free.

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

• Revision Notes
• Chapter 1 Matter In Our Surroundings

CBSE Class 9 Science Chapter 1 - Matter in Our Surroundings Revision Notes - Free PDF Download

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.

We also have provided the free pdf to download which will help the students to revise the chapter anytime, with or without the internet.

Download CBSE Class 9 Science Revision Notes 2024-25 PDF

Also, check CBSE Class 9 Science revision notes for All chapters:

Access Class 9 Science Chapter 1 - Matter in Our Surrounding Notes

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.

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STUDY MATERIALS FOR CLASS 9

Extra Questions for Class 9 Science Chapter 1 Matter in Our Surroundings

Extra questions for Class 9 Science Chapter 1 Matter in Our Surroundings with answers is given below. Our subject expert prepared these solutions as per the latest NCERT textbook. These questions will be helpful to revise the all topics and concepts. CBSE Class 9 extra questions are the most simple and conceptual questions that are prepared by subject experts for the students to study well for the final exams. By solving these extra questions, students can be very efficient in their exam preparations.

Matter in Our Surroundings Class 9 Science Extra Questions and Answers

Very short answer questions.

1. Define matter. Answer:  Anything that occupies space and has mass is called matter.

2. State different states of matter with an example. Answer:  Matter has 3 different states (i) Solid (ii) liquid (iii) gas

3. What is diffusion? Answer:  The intermingling of molecules of one substance with that of the other is called diffusion.

4. What happen to the rate of diffusion if the temperature is increased? Answer:  With increased temperature, the rate of diffusion also increases as the particles gain energy and vibrate more.

5. Name the state of matter that have the tendency to maintain their shape when subjected to outside force. Answer:  Solid.

6. Define melting point. Answer:  The temperature at which a solid melts to become liquid at the atmospheric pressure is called its melting point.

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

8. Define latent heat of vaporization. Answer:  Latent heat of vaporization is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.

9. Define latent heat of fusion. Answer:  Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at its melting point.

10. Define sublimation. Answer:  Sublimation is the change of gaseous state directly to solid state without going through liquid state and vice-versa.

11. What is dry ice? Answer:  Solid carbon dioxide obtained by cooling and applying pressure on carbon dioxide gas. It does not melt so it is called dry ice.

12. What is humidity? Answer:  The air holds water vapour, this air with water is called humid air and the phenomenon is called humidity.

13. Give two properties of solid. Answer:  (1) Solids have fixed shape and are rigid. (2) Solids cannot be compressed.

14. What will happen if the pressure is reduced on solid carbon dioxide (dry ice)? Answer:  If the pressure is reduced on solid carbon dioxide it will directly change into gaseous state without melting.

15. Name any three substances that show sublimation. Answer:  Ammonium chloride, camphor and naphthalene balls.

16. Sponge is solid, but we can still compress it. Why? Answer:  Sponge is a solid with minute pores in it. When we press the sponge the air present in these pores is released out and hence we are able to compress it.

17. What is normal atmospheric pressure? Answer:  The atmospheric pressure at sea level is 1 atmosphere and taken as the normal atmospheric pressure.

18. What is Kelvin? Answer:  Kelvin is the SI unit of temperature (0°C = 273 K).

19. Give two examples of diffusion. Answer:  Milk drops dissolved in water and perfume sprayed in a room.

20. Give the temperature at which water exists in two different phases/states. Answer:  At 0°C water can be in solid or in liquid state. At 100°C water can be in liquid or in gaseous state.

Short Answer Type Questions

1. Why do we see water droplets collected on the outer surface of a glass container, containing ice?

Answer:  The water vapour present in air, comes in contact with the cold outer surface of the container thereby condensing it to form water droplets.

2. Explain why solids have fixed shape but liquids and gases do not have fixed shape.

Answer:  Solids have fixed shape due to strong intermolecular force of attraction between them. The liquids and gases have molecules with less intermolecular force of attraction and hence they can flow and take shape of the container.

3. Liquids and gases can be compressed but it is difficult to compress solids. Why?

Answer:  Liquids and gases have intermolecular space, on applying pressure externally on them the molecules can come closer thereby minimizing the space between them. But in case of solids there is no intermolecular space to do so.

4. A balloon when kept in sun, bursts after some time. Why?

Answer:  The balloon has air filled in it. The balloon when kept in sun gets heated and the air inside it also gets heated. The molecules of air get energy, and vibrate faster thereby exerting large force on the walls of the balloon. Due to this expansion of gases the balloon bursts.

5. Why do people perspire a lot on a hot humid day?

Answer:  On a hot, humid day, due to the heat our body starts sweating for the cooling mechanism i.e., by evaporation and gets cooling effect. But the air cannot hold any more water on a humid day and therefore the sweat or perspiration is seen.

6. Distinguish between evaporation and boiling. Answer:

7. Why is it advisable to use pressure cooker at higher altitudes?

Answer:  At higher altitudes, the atmospheric pressure is low and the water boils very fast and evaporates at faster rate therefore the pressure is required to increase the cooking process and this is done by using pressure cooker which increases the pressure inside the container and cooks food faster.

8. What are fluids?

Answer:  The states of matter that can flow due to less intermolecular force of attraction, are liquids and gases and are called as fluids.

9. One kg cotton and one kg sand, which is more denser? Why?

Answer:  One kg sand is more denser than 1 kg cotton because density = mass/volume . The volume required by cotton is more than the sand and density and volume are inversely proportional.

10. Why is water liquid at room temperature?

Answer:  At room temperature, the molecules of water have some intermolecular force of attraction and the room temperature cannot provide sufficient heat for these molecules to overcome their force of attraction and therefore remain in liquid phase.

11. State the differences between solid, liquid and gas. Answer:

12. Cotton in solid but it floats on water. Why?

Answer:  Cotton has large number of pores, in which air is trapped. Hence reducing its density and increasing the volume. Therefore cotton floats on water. But when these pores get filled with water it starts sinking.

13. Why arc solids generally denser than liquids and gases?

Answer:  Density of a substance is given by a formula= Mass/Volume In case of solids the molecules are tightly packed and hence large mass is concentrated in very small volume. Hence their density is more. But in case of liquids and gases, their molecules have intermolecular space and hence they don’t have large mass concentrated in small volume. So the density of solids is generally more than that of the liquids and gases.

14. On a hot sunny day, why do people sprinkle water on the roof or open ground?

Answer:  During hot sunny day, the surface of roof or ground absorbs large amount of heat and remains hot, on sprinkling water on these surfaces, the water absorbs large amount of heat from the surface due to its large latent heat of vaporisation thereby allowing the hot surface to cool.

15. On a hot sunny dug why do we feel pleasant sitting under a tree?

Answer:  Tree has lot of leaves which constantly show transpiration. Transpiration is loss of water through small tiny pores of leaves called stomata. When this water comes on the surface of leaf the water evaporates thereby causing cooling effect. Therefore we feel pleasant sitting under the tree on a hot sunny day.

16. The temperature at which liquids change into vapours is very high, for example, water vaporises at 100°C then how is n possible for water to evaporate at room temperature or at are other temperature?

Answer:  The molecules of water present on the surface of the exposed area which are in very small fraction, gains the energy from the surrounding. With this higher kinetic energy they are able to break the force of attraction between them and hence get converted into vapour state. This phenomenon of change of a liquid into vapours that takes place at any temperature below its boiling point is called evaporation.

17. Name the factors that affect evaporation.

Answer:  The rate of evaporation will increase with (1) an increase of surface area, (2) an increase of temperature, (3) a decrease in humidity, (4) an increase in wind speed.

18. The melting point of ice is 273.16 K. What does this mean? Explain in detail.

Answer:  Ice is solid at 0°C i.e., 273° K. The molecules of ice are tightly packed. These molecules have to overcome the force of attraction with which they are held and hence they gain this heat from the surrounding but the temperature remains the same as their energy is used to overcome the force of attraction between the particles. The particles have their state and starts vibrating freely and a stage reaches when the solid ice melts and is converted to liquid state at the same temperature i.e., 273 K.

19. How is the high compressibility property of gas useful to us?

Answer:  The gases have high compressibility. This property is used in the following situation: (1) LPG (liquefied petroleum gas) is a fuel which is made up of petroleum gas. On compressing this petroleum gas it forms liquid. (2) Oxygen cylinders in the hospitals have compressed gas filled in it. (3) CNG (compressed natural gas) is a natural gas, methane, which is compressed and used as a fuel in vehicles and at home.

20. With the help of an example, explain how diffusion of gases in water is essential?

Answer:  The gases from the atmosphere diffuse and dissolve in water. Gases like oxygen and carbon dioxide diffuse in water, are essential for the survival of aquatic animals and plants. Animals breathe in this oxygen dissolved in water for their survival and plants can use carbon dioxide dissolved in water for photosynthesis.

Long Answer Type Questions

1. Pressure and temperature determine the state of a substance. Ex-plane this in detail.

Answer:  (i) Any matter i.e., solid, liquid or gas when experiences an increase in temperature then they change their state.

Take ice cubes in a beaker or heat them slowly, the temperature increases and the ice melts to form liquid. Heat this liquid further it will become steam.

(ii) On lowering down the temperature of any matter, show change in their state.

Take the steam that is coming out of a boiling water and allow it to cool down, it condenses to form water and on further cooling of this water we get ice.

(iii) On applying pressure and reducing temperature we can liquefy gases or change them into solid.

Example: Take carbon-dioxide gas, reduce its temperature and apply lot of pressure on it so that it changes into solid carbon dioxide, called diy ice, which is used as refrigerant for cooling. If the pressure on it is decreased it directly changes into gas.

In LPG cylinders, the petroleum gas is cooled and with lot of pressure changes it into liquid state. While using this LPG, we release the pressure exerted on it and hence it comes out in the form of gas.

2. Explain giving examples the various factors on which rate of evaporation depends.

Answer:  The rate of evaporation depends on the following factors: (1) Surface area: If the surface area is increased the rate of evaporation also increases. (a) To dry the clothes we spread them to dry faster. (b) Tea in saucer cools faster than in a cup. (2) Temperature: If the temperature is increased the rate of evaporation also increases. Due to increase in temperature the particles gain more kinetic energy and change their phase from liquid to gaseous. Water will evaporate faster in sun than in shade. (3) Humidity: It is the amount of water vapour present in air. The air can hold definite amount of water vapour, at a given temperature. If the amount of water vapour is high in the air then the rate of evaporation decreases. On hot and humid day, desert coolers are not effective as the air cannot hold any more moisture to get the cooling effect. (4) Wind speed: With the increase in wind speed, the rate of evaporation increases. The particles of water vapour move away with the wind, decreasing the amount of water vapour in the surrounding.

Value-Based Questions

1. Adil parked his bicycle on a sunny day in a parking stand of his school campus. When the school got over Adil saw his burst cycle type. Thereafter he kept less air in his cycle types and did not inflate them fully. (a) Why did the type burst? (b) Why is air compressible? (c) What value of Adil is reflected in the above act?

Answer:  (a) The tyre burst because the air inside the tyre got heated and therefore exerted pressure on the walls of the tyre. (b) Air is compressible because it has large intermolecular space. (c) Adil showed the value of intelligence, awareness and self responsibility.

2. Akshay’s friend visited his house in Mumbai and he was surprised to see air conditioners installed in all of his rooms. His friend advised Akshay to use water-coolers and save electricity. On this Akshay told, him that the water-cooler is not at all effective in coastal areas. (a) Why are water-cooler not effective in coastal areas? (b) What are the other two factors on which evaporation of water depends? (c) What value of Akshay’s friend is seen in this act?

Answer:  (a) Water coolers are not effective in coastal areas due to high rate of humidity. (b) The other two factors on which evaporation of water depends are temperature and surface area. (c) Akshay’s friend showed the value of concerned citizen, morally responsible and friendly in nature.

3. Sita lived in a village and could, not afford refrigerator in her house. She knew how to keep water cold and preserve all perishable items in her house. She kept wet cloth surrounding the earthen pot to keep water cool, she also kept vegetables fresh by keeping them in wet gunny bag and timely sprinkled water over it. (a) Why did Sita keep wet cloth surrounding the earthen pot? (b) Suggest one more method of keeping the house cool in summer. (c) What value of Sita is reflected in the above case?

Answer:  (a) The wet cloth gave the cooling effect to the pot, as the water in the cloth evaporated and evaporation causes cooling effect. (b) By sprinkling some water on the lawn/veranda of the house can keep the house cool. (c) Sita showed the value of responsible behaviour.

4. Shreya commutes in a CNG fitted van to school every day along with many other students. She told the van driver to get the CNG connection certified and timely checked it for any leakage or loose connection of pipes. She told the driver to be more careful during summers. (a) What is CNG? (b) Why should one be more careful with CNG cylinders during summer? (c) What value of Shreya is seen in the above act?

Answer:  (a) CNG is Compressed Natural Gas used as fuel. (b) During summers, the CNG connections and cylinder need to be checked because the gas expands due to heat and if there would be any leakage then it would cause fire in the vehicle. (c) Shreya showed the value of concerned citizen and morally responsible behaviour.

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NCERT Exemplar Class 9 Science Chapter 1 Matter In Our Surroundings

June 23, 2022 by Bhagya

NCERT Exemplar Class 9 Science Chapter 1 Matter In Our Surroundings are part of NCERT Exemplar Class 9 Science . Here we have given NCERT Exemplar Class 9 Science Solutions Chapter 1 Matter In Our Surroundings.

NCERT Exemplar Class 9 Science Solutions Chapter 1 Matter In Our Surroundings

Multiple Choice Questions

Question 1. Which one of the following sets of phenomena would increase on raising the temperature? (a) Diffusion, evaporation, compression of gases (b) Evaporation, compression of gases, solubility (c) Evaporation, diffusion, expansion of gases (d) Evaporation, solubility, diffusion, compression of gases Solution: (c) Rate of evaporation, diffusion and expansion of gases increase with increase in temperature.

Question 2. Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends she got confused. Help her to identify the correct set of conditions. (a) Low temperature, low pressure (b) High temperature, low pressure (c) Low temperature, high pressure (d) High temperature, high pressure Solution: (c) Gases can be compressed under low temperature and high pressure. Under these conditions the particles of gases come closer and liquefy.

Question 3. The property to flow is unique to fluids. Which one of the following statements is correct? (a) Only gases behave like fluids. (b) Gases and solids behave like fluids. (c) Gases and liquids behave like fluids. (d) Only liquids are fluids. Solution: (c) Gases and liquids flow due to less intermolecular force in the molecules. Gases and liquids take the shape of the container in which they are put.

Question 4. During summer, water kept in an earthen pot becomes cool because of the phenomenon of (a) diffusion (b) transpiration (c) osmosis (d) evaporation. Solution: (d) Earthen pot has small pores through which water keeps evaporating and evaporation causes cooling.

Question 5. A few substances are arranged in the increasing order of ‘forces of attraction’ between their particles. Which one of the following represents a correct arrangement? (a) Water, air, wind (b) Air, sugar, oil (c) Oxygen, water, sugar (d) Salt, juice, air Solution: (c) Forces of attraction between the particles increase in the order of gases < liquids < solids hence, the correct arrangement is oxygen, water, sugar.

Question 6. On converting 25°C, 38°C and 66°C to Kelvin scale, the correct sequence of temperature will be (a) 298 K, 311 K and 339 K (b) 298 K, 300 K and 338 K (c) 273 K, 278 K and 543 K (d) 298 K, 310 K and 338 K Solution: (a) K =25 °C + 273 Hence 25°C = 273 + 25 = 298 K 38°C = 273 + 38 = 311 K 66°C = 273 + 66 = 339 K

Question 7. Choose the correct statement of the following. (a) Conversion of solid into vapours without passing through the liquid state is called vapourisation. (b) Conversion of vapours into solid without passing through the liquid state is called sublimation. (c) Conversion of vapours into solid without passing through the liquid state is called freezing. (d) Conversion of solid into liquid is called sublimation. ’ Solution: (b) Conversion of vapours into solid without passing through the liquid state is called sublimation.

Question 8. The boiling points of diethyl ether, acetone and n-butyl alcohol are 35°C, 56°C and 118°C respectively. Which one of the following correctly represents their boiling points in Kelvin scale? (a) 306 K, 329 K, 391 K (b) 308 K, 329 K, 392 K (c) 308 K, 329 K, 391 K (d) 329 K, 392 K, 308 K Solution: (c): 35°C = 273 + 35 = 308 K 56°C = 273 + 56 = 329 K 118°C = 273 + 118 = 391 K

Question 9. Which condition out of the following will increase the evaporation of water? (a) Increase in temperature of water (b) Decrease in temperature of water (c) Less exposed surface area of water (d) Adding common salt to water Solution: (a): Rate of evaporation increases with increase in temperature of water.

Question 10. ln which of the following conditions, the distance between the molecules of hydrogen gas would increase? (i) Increasingpressureonhydrogencontained in a closed container. (ii) Some hydrogen gas leaking out of the container. (iii) Increasing the volume of the container of hydrogen gas. (iv) Adding more hydrogen gas to the container without increasing the volume of the container. (a) (i) and (iii) (b) (i) and (iv) (c) (ii) and (iii) (d) (ii)and(iv) Solution: (c) (ii) If some hydrogen gas is leaked from the container the remaining gas will occupy the whole space and the distance between the molecules will increase. (iii) If the volume of the container is increased, same number of molecules will occupy that space. Hence, the distance between the molecules will increase.

Short Answer Type Questions

Question 11. A sample of water under s^tudy was found to boil at 102°C at normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment. Solution: The sample of water boils at a higher temperature which shows that water is not pure. Due to impurities present in it water boils at a higher temperature. This water will freeze below 0°C.

Question 13. Fill in the blanks: (a) Evaporation of a liquid at room temperature leads to a ______ effect. (b) At room temperature the forces of attraction between the particles of solid substances are ______ than those which exist in the gaseous state. (c) The arrangement of particles is less ordered in the ______ state. However, there is no order in the state. (d) ______ is the change of gaseous state directly to solid state without going through the ______ state. (e) The phenomenon of change of a liquid into the gaseous state at any temperature below its boiling point is called ______. Solution: (a) Cooling (b) Stronger (c) Liquid, gaseous (d) Sublimation, liquid (e) Evaporation

Question 14. Match the physical quantities given in column A to their SI units given in column B.

Solution: (a) (iii) (b) (iv) (c) (v) (d) (ii) (e) (i)

Question 15. The non SI and SI units of some physical quantities are given in column A and column B respectively. Match the units belonging to the same physical quantity.

Solution: (a) (iv) (b) (iii) (c) (v) (d) (ii) (e) (i)

Question 16. ‘Osmosis is a special kind of diffusion’. Comment. Solution: In diffusion, the particles move from higher concentration to lower concentration without separation by a semipermeable membrane. In osmosis, the particles move from lower concentration to higher concentration (solvent to solution) when the two solutions are separated by a semipermeable membrane. Hence, osmosis is a special kind of diffusion involving movement of particles.

Question 17. Classify the following into osmosis/diffusion: (a) Swelling up of a raisin 9n keeping in water. (b) Spreading of virus on sneezing. (c) Earthworm dying on coming in contact with common salt. (d) Shrinking of grapes kept in thick sugar syrup. (e) Preserving pickles in salt. (f) Spreading of smell of cake being baked throughout the house (g) Aquatic animals using oxygen dissolved in water during respiration. Solution: (a) Osmosis (b) Diffusion (c) Osmosis (d) Osmosis (e) Osmosis (f) Diffusion (g) Diffusion

Question 18. Water as ice has a cooling effect, whereas water as steam may cause severe burns. Explain these observations. Solution: Water in the form of ice has low energy since water freezes at a lower temperature. When ice comes in contact with body it draws heat from the body and gives cooling effect. In case of steam, the water molecules have high energy. The high energy of steam is transformed as heat and may cause severe burns.

Question 19. Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment. Solution: The temperature of both boiling water and steam is 100°C but steam has more energy because of latent heat of vaporisation. Hence, steam is hotter than boiling water.

Question 22. (a) Conversion of solid to vapour is called sublimation. Name the term used to denote the conversion of vapour to solid. (b) Conversion of solid state to liquid state is called fusion; what is meant by latent heat of fusion? Solution: (a) Sublimation (b) Latent heat of fusion is the amount of heat required to change 1 kg solid into liquid at atmospheric pressure at its melting point.

Long Answer Type Questions

Question 24. lt is a hot summer day, Priyanshi and Ali are wearing cotton and nylon clothes respectively. Who do you think would be more comfortable and why? Priyanshi is wearing cotton clothes which are more comfortable in summers because cotton absorbs the sweat which causes cooling on evaporation. Ali is wearing nylon clothes which do not absorb sweat. Hence, Ali will be uncomfortable.

Question 25. You want to wear your favourite shirt to a party, but the problem is that it is still wet after a wash. What steps would you take to dry it faster? Solution: The process of drying the shirt can be made faster in the following ways : (a) Spread the shirt to increase the surface area which will increase rate of evaporation. (b) Put it in the sun to increase the temperature to increase the rate of evaporation. (c) Keep it under the fan to increase the wind speed which increases the rate of evaporation.

Question 26. Comment on the following statements: (a) Evaporation produces cooling. (b) Rate of evaporation of an aqueous solution decreases with increase in humidity. (c) Sponge though compressible is a solid. Solution: (a) Evaporation is a surface phenomenon. The particles from the surface of the liquid take energy from the surroundings and change into vapours which results in the decrease in energy of the surroundings. Hence, cooling effect is produced during evaporation.

(b) The amount of water present in the air is known as humidity. If the water vapour in air is already present in large amount, it is not able to take up more water through evaporation. Hence, the rate of evaporation of water will decrease. On a dry day, the air absorbs water more readily hence, the rate of evaporation is high on a dry day.

(c) A sponge is a solid but it has minute pores in which air is trapped. These pores make the sponge a soft material. When sponge is pressed, the air present in the pores comes out and the sponge is compressed.

Question 27. Why does the temperature of a substance remain constant during its melting point or boiling point? Solution: When a substance melts, it absorbs heat for the conversion of solid state into liquid state. As we continue heating, the heat supplied is used up in converting the solid state into liquid state by overcoming the forces of attraction between the particles and there is no change in temperature till the whole solid is converted into liquid. This heat absorbed by the solid which does not resitlt in increase in temperature, is called latent heat of fusion. When a liquid is heated, it starts converting into vapours.

Further heat given to the liquid is used in changing the state and there is no increase in the temperature till the liquid starts boiling. This heat is known as latent heat of vaporisation. Hence, the temperature of a substance remains constant at its melting point or boiling point untill all the substance melts or boils.

NCERT Exemplar Class 9 Science Solutions

• Chapter 1 Matter In Our Surroundings
• Chapter 2 Is Matter Around Us Pure
• Chapter 3 Atoms and Molecules
• Chapter 4 Structure of the Atom
• Chapter 5 The Fundamental Unit of Life
• Chapter 6 Tissues
• Chapter 7 Diversity in Living Organisms
• Chapter 8 Motion
• Chapter 9 Force and Laws of Motion
• Chapter 10 Gravitation
• Chapter 11 Work and Energy
• Chapter 12 Sound
• Chapter 13 Why do we Fall ill
• Chapter 14 Natural Resources
• Chapter 15 Improvement in Food Resources

We hope the NCERT Exemplar Class 9 Science Chapter 1 Matter In Our Surroundings will help you. If you have any query regarding NCERT Exemplar Class 9 Science Solutions Chapter 1 Matter In Our Surroundings, drop a comment below and we will get back to you at the earliest.

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Assertion and Reason Questions for Class 9 Science Chapter 1 Matter in Our Surroundings

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Table of Contents

Here we are providing assertion reason questions for class 9 science. This article covers assertion reason questions based on Class 9 Science Chapter 1 Matter in Our Surroundings . To check the answer, click on ‘ Show Answer ’ given below each question. After clicking it will expand.

Directions:  In each of the following questions, a statement of Assertion is given, and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as: (a) Both assertion and reason are true, and reason is the correct explanation of assertion. (b) Both assertion and reason are true, but reason is not the correct explanation of assertion. (c) Assertion is true, but reason is false. (d) Assertion is false, but reason is true.

Q.1. Assertion : A gas can easily be compressed by applying pressure. Reason : Since the inter-particle spaces between gases are very large, they can decrease by applying pressure.

Q.2. Assertion : Gases exert pressure on the walls of the container. Reason : The intermolecular force of attraction is very strong in gases.

Q.3. Assertion : It is easier to cook food at sea level as compared to higher altitudes. Reason : The boiling point of water increases at high altitudes.

Q.4. Assertion : When a solid melts, its temperature remains the same. Reason : The heat gets used up in changing the state by overcoming the forces of attraction between the particles.

Q.5. Assertion : The solids do not diffuse in air. Reason : The particles are loosely packed in solids.

Also read: Case Study Questions for Class 9 Science Chapter 1 Matter in Our Surroundings

Q.6. Assertion : The boiling point of water is 100 C. Reason : The boiling point of water increases at higher altitudes.

Q.7. Assertion : The conversion of a solid directly into a gas is known as sublimation. Reason : Naphthelene does not leave residue when kept open for sometime.

Q.8. Assertion : lce floats on water. Reason : Liquids have lower density than solids.

Q.9. Assertion : Camphor burns with a lot of residue. Reason : Camphor undergoes sublimation.

Q.10. Assertion : The rate of evaporation increases with increase in temperature. Reason: Increase in temperature decreases the kinetic energy of the particles.

Also read: Topicwise Important Questions for Class 9 Science Chapter 1 Matter in Our Surroundings

Q.11. Assertion : Liquids diffuses more easily as compared to gases. Reason : Intermolecular forces are greater in liquids than in gases.

Q.12. Assertion : Steam is better the boiling water for heating purposes. Reason : Steam contains more heat in the form of latent heat than boiling water.

Q.13. Assertion : Gases diffuses more easily as compared to liquids. Reason : Intermolecular forces are greater in solids.

Q.14. Assertion : There is a change in the temperature of the substance when there it undergoes a change in state through it is still being heated. Reason : The heat supplied is either absorbed as a latent heat of fusion or a latent heat of vapourisation.

Q.15. Assertion : When Sugar and Salt are kept in a container, they take the shape of the container. Reason : Sugar is liquid.

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6 thoughts on “ Assertion and Reason Questions for Class 9 Science Chapter 1 Matter in Our Surroundings ”

Very nice questions

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• CBSE Notes For Class 9
• Class 9 Science Notes
• Chapter 1: Matter In Our Surroundings

Matter In Our Surroundings Class 9 Notes - Chapter 1

Cbse class 9 science notes chapter 1 matter in our surroundings, states of matter.

• Matter can be classified as solid, liquid or gas on the basis of interparticle forces and the arrangement of particles.
• These three forms of matter are interconvertible by increasing or decreasing pressure and temperature.  For example, ice can be converted from solid to a liquid by increasing the temperature.

For more information on Matter Around Us, watch the below video

To know more about the States of Matter, visit here .

For more information on the States of Matter, watch the below video

Atomic View of the Three States of Matter

Physical Nature of Matter

• A physical property is an aspect of matter that can be observed or measured without changing its nature or composition.
• It is independent of the amount of matter present.
• Physical properties include appearance, colour, odour, density, texture, melting point, boiling point, solubility, etc.

For more information on Physical Nature of Matter, watch the below video

To know more about the Physical Nature of Matter, visit here .

Characteristics of Particles of Matter

Matter is anything that has mass and occupies space.

• Everything that we can touch, see, hear, taste and also smell is matter.
• It is made up of really tiny particles which cannot be seen through the eye.

For more information on Characteristics of Particles of Matter, watch the below video

The particles of which the matter is comprised influence its state and properties (physical and chemical).

1. Particles of matter have spaces between them

• This characteristic is one of the concepts behind the solubility of a substance in other substances. For example, on dissolving sugar in water, there is no rise in the water level because the particles of sugar get into the interparticle spaces between the water particles.

2.  Particles of matter are always in motion

• Particles of matter show continuous random movements due to the kinetic energy they possess.
• A rise in temperature increases the kinetic energy of the particles, making them move more vigorously.

3.  Particles of matter attract each other In every substance, there is an interparticle force of attraction acting between the particles. To break a substance, we need to overcome this force. The strength of the force differs from one substance to another.

To know more about the Characteristics of Particles of Matter, visit here .

When the particles of matter intermix on their own with each other, the phenomenon is called diffusion . For example, spreading of ink in water.

• During diffusion, the particles occupy the interparticle spaces.
• The rate of diffusion increases with an increase in temperature due to increase in the kinetic energy of the particles.

To know more about Diffusion, visit here .

Can Matter Change Its State?

Effect of change of temperature on the state of matter.

On increasing the temperature, the kinetic energy of the particles of the matter increases, and they begin to vibrate with higher energy. Therefore, the interparticle force of attraction between the particles reduces, and particles get detached from their position and begin to move freely.

• As a result, the state of matter begins to change.
• Solids undergo a phase change to form liquids.
• Similarly, liquids also undergo a phase change to form gases.

To know more about the Changing State of Matter, visit here .

Melting Point

The melting point of a solid is defined as the temperature at which solid melts to become liquid at the atmospheric pressure.

• At the melting point, these two phases, i.e., solid and liquid, are in equilibrium, i.e., at this point, both solid state and liquid state exist simultaneously.

When two atoms collide to create a heavier atom, such as when two hydrogen atoms combine to create one helium atom, this process is known as fusion. This process generates enormous amounts of energy, many times more than fission, and powers the sun. Furthermore, it doesn’t generate radioactive fission products.

The melting point at which ice, a solid, turns to water, a liquid, is 32°F (0°C).

Boiling Point

The boiling point of a liquid is defined as the temperature at which the vapour pressure of the liquid is equal to the atmospheric pressure.

The boiling point for any material is the temperature point at which the material transforms into the gas phase in the liquid phase. This happens at 100 degrees centigrade for water. The Celsius scale was in fact created on the basis of the ice/water melting point and the liquid water/vapor boiling point.

Read more:   Celsius to Kelvin

Latent Heat of Fusion

It is the amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point.

Latent Heat of Vaporisation

It is the amount of heat energy that is required to change 1 kg of a liquid into gas at atmospheric pressure at its boiling point.

Sublimation

The transition of a substance directly from its solid phase to gaseous phase without changing into the liquid phase (or vice versa) is called sublimation.

Effect of Change in Pressure on the State of Matter

By applying pressure, the interparticle spaces between particles of matter decrease. Thus, by applying pressure and reducing temperature, we can convert a solid to liquid and a liquid to gas.

Flowchart for Inter-Conversion of the Three States of Matter

Evaporation

The phenomenon by which molecules in liquid state undergo a spontaneous transition to the gaseous phase at any temperature below its boiling point is called evaporation.

• For example, the gradual drying of damp clothes is caused by the evaporation of water to water vapour.

For more information on Evaporation, watch the below video

To know more about Evaporation, visit here .

Factors Affecting Evaporation

• Temperature: The rate of evaporation increases with an increase in temperature.
• Surface area: The rate of evaporation increases with an increase in surface area.
• Humidity: The rate of evaporation decreases with an increase in humidity.
• Wind speed: The rate of evaporation increases with an increase in wind speed.

To know more about Factors Affecting Rate of Evaporation, visit here .

Cooling Due to Evaporation

During evaporation, the particles of a liquid absorb energy from the surroundings to overcome the inter-particle forces of attraction and undergo phase change. The absorption of heat from the surrounding makes the surroundings cool.

For example, sweating cools down our body.

Applications of Evaporative Cooling

• To keep water cool, it is kept in earthenware containers. Similar to the pores in cotton fabric, the pores in the earthen pot’s surface area allow for more evaporation.
• To keep our bodies cool, we sweat a lot. Evaporation is what transpiration ultimately is. Our body’s water evaporates, using energy in the process and lowering our body temperature as a result.
• We dress in cotton during the summer. Since cotton is a powerful water absorbent, it allows more perspiration to come into touch with the air, promoting more evaporation. We have a cooling effect when wearing cotton clothing because of this.
• NCERT Solutions for Class 9 Science Chapter 1 Matter In Our Surroundings
• Important Questions for Class 9 Science Chapter 1 –Matter In Our Surroundings
• NCERT Exemplar Class 9 Science Solutions for Chapter 1 – Matter In Our Surroundings
• Matter In Our Surroundings
• Maths Notes For Class 9
• CBSE Class 9 Social Science Notes

Frequently Asked Questions on CBSE Class 9 Biology Notes Chapter 1 Matter in Our Surroundings

What is the ‘latent heat of fusion’.

The latent heat of fusion is the enthalpy change of any amount of substance when it melts.

What does ‘sublimation critical point’ mean?

The sublimation critical point refers to the maximum or minimum temperature and pressure beyond which the state of the matter cannot be changed.

What does ‘interconversion of matter’ mean?

Interconversion of matter refers to the change from one state to another. It is a process by which matter changes from one state to another and back to its original state without any change in its chemical composition.

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