case study questions class 9 science chapter 4

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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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Class 9 Science Chapter 4 Case Based Questions - Structure of the Atom

(I) Read the given passage and answer the questions based on the passage and related studied concepts. Atom consists of electrons, protons and neutrons. J.J. Thomson proposed that electrons are embedded in a positive charge uniform sphere. Rutherford a-scattering experiment led to discovery of nucleus in the centre of atom which is positively charged and whole mass of atom is concentrated in the nucleus. Neil Bohr proposed that electrons are distributed in different shells in M, N... with discrete energy around the nucleus. If atomic shell is complete, atom will be stable and less reactive. Electrons are negatively charged, protons are positively charged, neutrons are neutral. Valency is the combining capacity of an atom. Atomic number is equal to number of protons in an atom. The mass number of an atom is equal to sum of number of protons and neutrons in the nucleus. Isotopes have same atomic number but different mass numbers. Isobars have same mass number but different atomic numbers. Elements are defined by number of protons (atomic number) they possess. Q1: Which of the following does not contain neutron?  (a)  Al (b)  Na (c) H (d)  Mg Ans:  Hydrogen (H) does not contain neutron.

Q2: What is the atomic number of Al 3+ , if it has 13 protons, 10 electrons, 14 neutrons? (a)  13 (b)  10 (c)  14 (d)  27 Ans: (a)  13, Atomic number is equal to number of protons.

Q4: Isotopes differ in which sub-atomic particles? Ans: Neutrons

Q2: Name the element in which second shell has twice electrons than 1 st shell. Ans:  C(2, 4)

Q3: How does valence electrons vary from Li to Ne? Ans: Valence electrons increase from Li to Ne.

Q4: Name the element which has 7 valence electrons. Ans: Fluorine (F) 2, 7.

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Case Based Question Answer: Structure of the Atom Free PDF Download

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CBSE Class 9 Science Important Case Study Questions with Answers for Term 2 Exam 2022 (PDF)

Check important case study questions of cbse class 9 science to prepare for the cbse term 2 exam 2022. all these questions have been put together by subject experts..

CBSE Class 9 Term 2 Exam 2022:  Important case based questions for CBSE Class 9 Science are provided here students to prepare for the upcoming Term 2 Exam 2022. All the questions provided below are curated by the subject experts. These questions are really helpful to revise important concepts and prepare the case study questions for the exam. Answers to all questions have been provided for reference. So, students should practice the chapter-wise questions to clearly understand the right way to attempt the case based questions. Download the chapter-wise questions in PDF.

Check some of the important case study questions below:

Q. Read the following and answer the questions :

A student was asked by his teacher to verify the law of conservation of mass in the laboratory. He prepared 5% aqueous solutions of NaCl and Na 2 SO 4 . He mixed 10 mL of both these solutions in a conical flask. He weighed the flask on a balance. He then stirred the flask with a rod and weighed it after sometime. There was no change in mass.

• Was the student able to verify the law of conservation of mass?
• If not, what was the mistake committed by him?
• In your opinion, what he should have done?
• What is the molar mass of Na 2 SO 4 ?
• No, he could not verify the law of conservation of mass in-spite of the fact that there was no change in mass.
• No chemical reaction takes place between NaCl and Na 2 SO 4 . This means that no reaction actually took place in the flask.
• He should have performed the experiment by using aqueous solutions of BaCl 2 and Na 2 SO 4 . A chemical reaction takes place in this case and a white precipitate of BaSO 4 is formed.
• Will the weight of the precipitate be the same as that of the reactants before mixing?
• If not, what she should have done?
• Which law of chemical combination does this support?
• State the law of conservation of mass.
• No, it will not be the same.
• She should have weighed the total contents of the beaker after the reaction and not the precipitate alone.
• It supports the law of conservation of mass.
• Mass can neither be created nor destroyed during a chemical reaction.

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NCERT Solutions for Class 9 Science Chapter 4 Structure of the Atom

NCERT Solutions for Class 9 Science Chapter 4 Structure of the Atom in Hindi and English Medium prepared for new session 2024-25. Class 9 Science chapter 4 is modified and revised as per the new rationalised NCERT textbooks issued for academic year 2024-25.

Class 9 Science Chapter 4 Question Answers

• Class 9 Science Chapter 4 Exercises
• Class 9 Science Chapter 4 Intext Questions
• Class 9 Science Chapter 4 Extra Questions
• Class 9 Science Chapter 4 Hindi Medium
• Class 9 Science Chapter 4 Notes in English
• Class 9 Science Chapter 4 Notes in Hindi
• Class 9 Science Chapter 4 NCERT Book
• Class 9 Science NCERT Solutions
• Class 9 all Subjects NCERT Solutions

NCERT Class 9 Science textbook, Chapter 4 Structure of the Atom delves into the structure and components of atoms, providing insight into the fundamental building blocks of matter. The main topics covered in Chapter 4 are the concept of the atom as the basic unit of matter, Dalton’s Atomic Theory that is a brief overview of Dalton’s atomic theory and its postulates. Here we will study about Charged Particles in Matter which provides the explanation of charged particles in matter, including electrons, protons, and neutrons.

Distribution of Electrons in Different Orbits (Shells) Class 9 students learn in chapter 4 about explanation of electron distribution in shells or energy levels and introduction to the K, L, M, and N shells. It also explains the definition of valency and its significance, determining valency based on electron distribution. Here, we learn about Atomic Number and Mass Number with explanation of atomic number and its significance, definition of mass number and how it is determined. Class 9 science chapter 4 explores about the definition of isotopes and examples, explanation of isotopic notation.

A recap of the main concepts and ideas presented in Chapter 4 Structure of the Atom, provides a foundational understanding of the structure and components of atoms. It introduces students to the historical development of atomic models and sets the stage for further exploration of atomic and molecular structures in subsequent chapters and classes.

Preparing for NCERT Class 9 Science Chapter 4 Structure of the Atom, requires a proper approach to understanding the fundamental concepts related to atomic structure. Here are some steps and planning strategies for students to prepare this chapter 4 of 9th science effectively. First of all, read the Chapter Thoroughly, begin by reading the chapter carefully from the NCERT textbook. Pay attention to definitions, examples, and key points. While reading, take detailed notes on important concepts, definitions, and key terms.

To make science easy, summarize the main ideas of each section. Understand the historical development of atomic models, including Dalton’s atomic theory, J.J. Thomson’s experiments, Rutherford’s gold foil experiment, and Bohr’s model. Know the key contributions of these scientists. Study the components of an atom, including electrons, protons, and neutrons. Understand their properties, locations, and charges. Learn about Bohr’s model of the hydrogen atom, including the concept of energy levels or orbits and how it explains spectral lines.

Class IX Science chapter 4 Exercise and Intext question answers in PDF format to free download. Class 9 UP Board students also get here UP Board Solutions. Class 9 Science chapter 4 Intext questions given on Page 43 or Page 49 or Page 50 or Page 52 or Page 53 and Exercises in English Medium are available.

You can download these solutions from Page 53 ke Uttar or Page 56 ke Uttar or Page 57 ke Uttar or Page 58 ke uttar or Page 59 ke Uttar or Page 60 ke Uttar and Abhyaas ke Uttar to study online or in PDF file format. NCERT Solutions and Offline Apps for all other subjects based on latest CBSE Syllabus are also available to download.

Electron Distribution and Valency Understand how electrons are distributed in different shells or energy levels (K, L, M, N). Learn the maximum number of electrons each shell can hold. Know the definition of valency and how it relates to electron distribution. Practice determining the valency of elements based on their electron configuration. Learn how to calculate the number of protons, electrons, and neutrons in an atom. Isotopes: Understand isotopic notation.

Practice solving numerical problems related to atomic structure, atomic number, mass number, and electron distribution. Work through exercises and examples in the textbook. Utilize diagrams and visual aids in the chapter to help understand atomic structures and models. Supplement your learning with online resources, videos, and interactive simulations related to atomic structure. These can provide additional clarity. Group study can offer different perspectives and help reinforce your understanding.

Regularly revise your notes and the key points of the chapter 4 in 9th science. Repetition is key to retaining information. Closer to your exams, practice solving sample papers and previous year’s question papers to familiarize yourself with the exam pattern and practice time management. If you have doubts or find certain topics challenging, don’t hesitate to seek help from your teacher or classmates. Clarify your doubts as soon as possible. By following these planning strategies and staying organized, you can effectively prepare for NCERT Class 9 Science Chapter 4 and build a strong foundation in atomic structure and chemistry concepts.

Extra Questions on 9th Science Chapter 4

Is atomic number of an atom always equal to the number of electrons.

No, it is the case when the atom has no charge. In case of cation (positively charged), atomic number is more than the number of electrons and in case of anion (negatively charged), it is less than the number of electrons.

Nucleus of an atom has positive charge on it. Establish.

This can be established on the basis of Rutherford scattering experiment. Since some alpha particles were repelled by the nucleus of the atom, it is expected to have the same charge as on alpha particles. Therefore, nucleus of an atom has positive charge.

Were neutrons known at the time Rutherford performed the scattering experiment?

No, these were discovered later on by Chadwick in 1931 whereas scattering experiment was performed by Rutherford in 1911.

Why are isotopes of an element chemically similar?

Isotopes of an elements have same number of electrons and therefore, same value shell electronic distribution. Since the chemical properties of the atoms are related to valence shell configurations, the isotopes are chemically similar.

Why do elements which exist as isotopes have fractional atomic masses?

The different isotopes of an element differ in their mass number as well as atomic masses. In order to represent the atomic mass of the element, we have to consider average of the atomic masses of the different isotopes and also the ratio in which these are present. In most of the cases, the average comes out to be in fraction. Therefore, these elements have fractional atomic masses.

Why is a proton not a universal particle like electron?

A proton is the positively charged residue left when hydrogen gas is enclosed in the in the discharge tube. For the other gases, the positive residues formed contain different number of protons. Therefore, proton is not a universal particle like electron.

Tiwari Academy plays a significant role in helping students prepare for NCERT Class 9 Science Chapter 4. Here’s how Tiwari Academy can assist students in their preparation for this chapter. It provides detailed solutions to all the questions and exercises in the NCERT Class 9 Science textbook for Chapter 4. These solutions can help students understand how to approach and solve different types of problems related to the structure of atoms.

Important Questions on 9th Science Chapter 4

What are the limitations of j.j. thomson’s model of the atom.

According to J.J. Thomson’s model of an atom, an atom consists of a positively charged sphere with electrons embedded in it. However, it was later found that the positively charged particles reside at the center of the atom called the nucleus, and the electrons revolve around the nucleus.

What are the limitations of Rutherford’s model of the atom?

According to Rutherford’s model of an atom, electrons revolve around the nucleus in fixed orbits. But, an electron revolving in circular orbits will not be stable because during revolution, it will experience acceleration. Due to acceleration, the electrons will lose energy in the form of radiation and fall into the nucleus. In such a case, the atom would be highly unstable and collapse.

Define valency by taking examples of silicon and oxygen.

The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom of that element. If the number of valence electrons of the atom of an element is less than or equal to four, then the valency of that element is equal to the number of valence electrons. For example, the atom of silicon has four valence electrons. Thus, the valency of silicon is four. On the other hand, if the number of valence electrons of the atom of an element is greater than four, then the valency of that element is obtained by subtracting the number of valence electrons from eight. For example, the atom of oxygen has six valence electrons. Thus, the valency of oxygen is (8 − 6) i.e., two.

Explain Atomic number with examples.

Atomic number: The atomic number of an element is the total number of protons present in the atom of that element. For example, nitrogen has 7 protons in its atom. Thus, the atomic number of nitrogen is 7.

What do you understand by isobars?

Isobars: They are atoms of different elements having same mass number but different atomic number. For example calcium, atomic number 20 and argon, atomic number 18. The number of electrons in these atoms is different, but the mass number of both these elements is 40. That is, the total number of neutrons is the same in the atoms of this pair of elements.

If Z = 3, what would be the valency of the element? Also, name the element.

By Z = 3, we mean that the atomic number of the element is 3. Its electronic configuration is 2, 1. Hence, the valency of the element is 1 (since the outermost shell has only one electron). Therefore, the element with Z = 3 is lithium.

NCERT Solutions for Class 9 Science Chapter 4 Structure of the Atom Intext Questions and chapter end exercise question answers are given below to free download. All the solutions are free to download without any registrations or login. We have updated all the contents on the basis of user’s suggestions and Feedback received from last academic session.

The Tiwari Academy website and apps offer explanations and videos that break down complex concepts in the chapter. Visual aids and clear explanations can help students grasp difficult topics more easily. It also provide historical context and explanations for the development of atomic models, making it easier for students to understand the evolution of atomic theory. The platform offer visual representations and interactive simulations of atomic structures, which can enhance students’ understanding of the arrangement of electrons, protons, and neutrons within an atom.

Questions related to class 9 science chapter 4, atomic structure and atomic models are frequently included in Class 9 Science examinations. Students can expect to see questions about atomic components, electron distribution, atomic number, and mass number in their exams. The chapter covers the historical development of atomic models, including Dalton’s atomic theory, J.J. Thomson’s experiments, Rutherford’s gold foil experiment, and Bohr’s model. Understanding the history of atomic theory is often tested in exams.

Question 1: An electron is regarded as a universal particle. Explain. Answer 1: The value of charge (e) and mass (m) of the electron always remain the same whatever may be the source of their emission. In the discharge tube, the electrons may be emitted either from the cathode or form the gas enclosed in the discharge tube. Whatever may be the metal which forms the cathode or the gas present in the discharge tube, these values remain the same. Therefore, electron is regarded as a universal particle.

Question 2: Why do the element helium, neon and argon have zero valency? Answer 2: Helium has two electrons in its only energy shell (K-shell). The other two elements have eight electrons in their valence shells. Since these are the maximum number of electrons which the atoms of these elements can have therefore, they do not have any urge or desire to take part in chemical combination. These elements are known as zero valent elements. They have therefore, valency equal to zero.

Class 9 Science chapter 4 bridges the gap between chemistry and physics by introducing concepts related to atomic structure. It sets the stage for students to explore topics like the periodic table, chemical bonding, and atomic physics in later classes. Knowledge of atomic structure is relevant to various scientific fields, including chemistry, physics, and materials science. Exams include questions that require students to apply their understanding of atomic structure to real-world scenarios. A strong foundation in Chapter 4 is, therefore, essential for success in future science studies.

Finally, the NCERT Class 9 Science Chapter 4, Structure of the Atom, is important not only for scoring well in exams but also for laying the groundwork for a deeper understanding of chemistry and physics concepts. Students should dedicate time and effort to comprehensively learn the concepts presented in this chapter to ensure success in their science studies.

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• Important Questions for CBSE Class 9 Science Chapter 4 - Structure of the Atom

CBSE Class 9 Science Chapter-4 Important Questions - Free PDF Download

Important Questions for Class 9 Science Chapter 4 the structure of the atom is created by subject matter experts at Vedantu. The main concept behind creating the important questions for the chapter to enable students to prioritize the concepts of chapter introduced in Science Class 9. The important questions of structure of atom Class 9 are prepared to give a better conceptual understanding. With the help of Class 9 Science Chapter 4 important questions, it would be easy to assume the type of questions will be asked in the chapter exam. The language used while preparing the important questions is proficient and understandable by a Class 9 student. Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths and Science Students who are looking for the better solutions ,they can download Class 9 Maths NCERT Solutions and Class 9 Science NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.

Download CBSE Class 9 Science Important Questions 2023-24 PDF

Also, check CBSE Class 9 Science Important Questions for other chapters:

Important Topics Covered In Class 9 Science Chapter 4 - Structure of the Atom

The following is a list of some of the important topics and subtopics that students will come across while studying Chapter 4 - Structure of the Atom. Students are advised to ensure that they have covered all these topics while preparing for the exam as questions are likely to be asked from them.

Introduction

Charged Particles In Matter

The Structure of An Atom

The Thomson's Model of An Atom

Rutherford's Model of An Atom

Drawbacks of Rutherford's Model of An Atom

Bohr’s Model of An Atom

How Are Electrons Distributed In Different Orbits?

Atomic Number And Mass Numbers

Study Important Questions for Class 9 Science Chapter 4 – Structure of Atoms

Very short answer questions (1 mark).

1. What are canal rays?

Ans: Positively charged rays discovered by E. Goldstein are called canal rays.

2. If an atom contains one electron and one proton, will it carry any charge or not?

Ans: A single electron contains one negative charge and one single proton contains one positive charge so they are neutralized by each other. That atom will not contain any charge.

3. Name the three sub-atomic particles of an atom.

Ans: Three subatomic particles of an atom are Proton, Neutron and Electron.

4. Rutherford’s alpha-particle scattering experiment was responsible for the discovery of

 Atomic Nucleus

 Electron

 Proton 

 Neutron

Ans: (d) Proton

5. Isotopes of an element have

 The same physical properties

 Different chemical properties

 Different number of neutrons

 Different atomic numbers

Ans: (a) The same physical properties.

6. Number of valence electrons in $C{{l}^{-}}$ ion are:

7. Which one of the following is a correct electronic configuration of sodium?

 8,2,1

 2,1,8

 2,8,1

Ans : (b) 2,8

8. Atomic Number of an element is equal to:

 Number of Protons

 Number of electrons

 Number of neutrons

 Both (a) and (b)

Ans: (a) Number of Protons

9. The charge of proton $({{p}^{+}})$ is:

$+1.6\times {{10}^{-19}}C$ 

$-1.6\times {{10}^{-19}}C$

$+1.6\times {{10}^{19}}C$

$-1.6\times {{10}^{19}}C$

Ans : (a) $+1.6\times {{10}^{-19}}C$

 10. ${}_{10}^{20}Ne$ and ${}_{10}^{22}Ne$ are

 Isotopes

 Isobars

 Isotones

Ans: (a) Isotopes

 11. Helium $\left( {}_{2}^{4}He \right)$ has:

 $2P+$ and $2n{}^\circ $

 $2P+$ and $4n{}^\circ $

 $4P+$ and $2n{}^\circ $

Ans: (a) $2P+$ and $2n{}^\circ $

 12. In which form is oxygen available?

 ${{O}^{2-}}$ 

 ${{O}^{2+}}$

 Both (a) and (c)

Ans: (a) ${{O}^{2+}}$

 13. How many electrons does $N{{a}^{+}}$ has in its outermost shell?

Ans: (d) 8 

 14. Atomic number of an element during a Chemical reaction.

 Increases

 Remain Constant

 Decreases

 May be (a) or (c)

Ans: (b) Remain constant

 15. The molecular formula for Aluminum chloride is 

 $A{{l}_{3}}Cl$

 $AlC{{l}_{3}}$

 $AlC{{l}_{3}}$ 

 Both (b) and (c)

Ans: (c) $AlC{{l}_{3}}$

 16. Atomicity of fluorine is:

Ans : (b) 2

 17. Molecular formula for calcium fluoride is-

$Ca{{F}_{2}}$ 

 $CaF$

 $C{{a}_{2}}F$

 $2CaF$

Ans: (a) $Ca{{F}_{2}}$

 18. Electronic configuration of calcium is

 2,8,8,2

 2,8,6,4

 2,8,7,1

 2,8,1,7

Ans: (a) 2,8,8,2

  19. Nitrogen is:

 Monatomic

 Diatomic

 Triatomic

 Tetratomic

Ans: (b) Diatomic

Short Answer Question (2 Marks)

1. On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.

Ans: As per Thomson’s model of an atom, the number of electrons and the number of protons are equal in an atom. Electrons are positively charged and protons are negatively charged, hence the + and – charges are neutralized by each other that makes atoms neutral as a whole.

2. On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?

Ans: The subatomic particle proton is present in the nucleus of an atom according to Rutherford’s model of an atom.

3. Draw a sketch of Bohr’s model of an atom with three shells.

Ans: Bohr’s model of an atom with three shells is as follows:

4. What do you think would be the observation if the $\alpha -$ particle scattering experiment is carried out using a foil of a metal other than gold?

Ans : If the $\alpha -$ particle scattering experiment is carried out using a foil of a metal other than gold we will get a different observation. 

5. Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?

Ans: The atomic mass of an atom is the sum of masses of protons and neutrons present in its nucleus.

Given that the mass of the helium atom is 4 u and two protons present in its nucleus.

So the number of neutrons will be

$\text{Number of neutrons = atomic mass }-\text{ number of protons}$ 

$\Rightarrow \text{Number of neutrons = 4}-2$

$\therefore \text{Number of neutrons = }2$

Therefore, the helium atom has 2 neutrons.

6. Write the distribution of electrons in carbon and sodium atoms.

Ans: Atomic number of carbon is 6 and the atomic number of sodium is 11.

So distribution of electrons in carbon atom is 6 = 2,4

Distribution of electrons in the sodium atom is 11 = 2,8,1.

7. If K and L shells of an atom are full, then what would be the total number of electrons in the atom?

Ans: K shell contains total 2 electrons and L shell contains maximum 8 electrons. If K and L shells of an atom are full, then the total number of electrons in the atom will be 10.

8. If number of electrons in an atom is 8 and number of protons is also 8, then

What is the atomic number of the atom? 

Ans: The atomic number of an atom is equal to the number of protons or electrons present in its nucleus. So the atomic number of an atom with 8 electrons and 8 protons is 8.

What is the charge on the atom?

Ans: A single electron contains one negative charge and one single proton contains one positive charge. There are equal numbers of electrons and protons in an atom so they neutralize each other. The atom will be neutral.

9. With the help of Table 4.1, find out the mass number of oxygen and Sulphur atoms.

Ans : The mass number of an atom is equal to the sum of protons and neutrons present in its nucleus. 

\[Mass\text{ }number\text{ }of\text{ }oxygen=8+8\] 

\[Mass\text{ }number\text{ }of\text{ }oxygen=16\] 

\[Mass\text{ }number\text{ }of\text{ Sulphur}=16+16\] 

\[Mass\text{ }number\text{ }of\text{ Sulphur}=32\]

10. What are the limitations of J.J. Thomson’s model of the atom?

Ans: The J.J. Thomson’s atomic model failed to explain the organization of electrons in an atom.

11. $N{{a}^{+}}$ has completely filled K and L shells. Explain.

Ans: Sodium $(Na)$ has atomic number 11, so the electronic configuration of $Na$ is 2,8,1.

It has a single electron in the outermost shell, when it gives away that electron it becomes $N{{a}^{+}}$ and has electronic configuration 2,8. Also the K shell contains a total 2 electrons and the L shell contains a maximum of 8 electrons. So $N{{a}^{+}}$ has completely filled K and L shells.

12. If $z=3$, what would be the valency of the element? Also, name the element.

Ans : $z=3$ represents that element has 3 electrons in its shells. The electronic configuration is 2,1. It means the outermost shell electron has 1 electron, so its valency is 1. The element is Lithium.

 Composition of the nuclei of two atomic species X and Y are given as under

13. Give the mass number of X and Y. What is the relation between the two species?

Ans: The mass number of an atom is equal to the sum of protons and neutrons present in its nucleus.

So the mass number of X is $=6+6=12$ 

Mass number of Y is $=6+8=14$ 

Number of protons is the same in X and Y but the atomic numbers are different. X and Y are isotopes.

 For the following statements, write T for True and F for False.

 J.J. Thomson proposed that the nucleus of an atom contains only nucleons.

 A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.

The mass of an electron is about 12000 times that of proton.

 An isotope of iodine is used for making tincture iodine, which is used as a medicine.

14. The nucleus of an atom of Bi – 210 (atomic number = 83) emits $\beta -$ particle and becomes a polonium nuclide. Write as equation for the nuclear change described.

Ans : Whenever a $\beta -$particle emits from the nucleus of an atom, the atomic number of that atom is increased by 1 but the mass number remains the same.

So when a $\beta -$particle emits from Bi – 210 (atomic number = 83) it becomes polonium nuclide. The equation for the nuclear change is as follows:

${}_{83}^{210}Bi\to {}_{84}^{210}Po+{}_{-1}^{0}e$.

16. How can one conclude that electrons are fundamental particles?

Ans: The $\dfrac{e}{m}$ ratio of electrons remains similar irrespective of the nature of gas and electrodes inside the discharge tube. So we can conclude that electrons are fundamental particles.

17. What happens to the nucleus of an atom when it emits a $\gamma -$ ray?

Ans: There is no change in mass or charge of nuclide when it emits $\gamma -$ ray. The energy of the nucleus decreases equal to the energy of photons emitted.

  18. Write the electronic configuration of following ions:

 $C{{l}^{-}}$ 

Ans: Electronic configuration of $C{{l}^{-}}$ ion is 2,8,8.

Ans : Electronic configuration of $Mg$ion is 2,8,2.

 $A{{l}^{3+}}$

Ans : Electronic configuration of $A{{l}^{3+}}$ ion is 2,8.

 $O$ 

Ans: Electronic configuration of $O$ is 2,6.

19. State Mendeleev’s periodic law? 

Ans: Mendeleev’s Periodic law states that the properties of elements are periodic functions of their atomic mass. Properties of elements depend on the atomic mass.

20. Define ionization energy and electron affinity?

Ans : Ionization energy of a component is that the amount of energy that has got to be supplied to at least one mole of the element within the gaseous state to get one mole of caters within the gaseous state.

Electron affinity point is that the energy change that accompanies the formation of 1 mole of anions within the gaseous state from one mole of the atoms of the element within the gaseous state.

21. Why is atomic number is more important than atomic weight in predicting the chemical properties of elements?

Ans: Atomic number is that the number of protons in an atom and through a reaction the number of protons remains unchanged. Atomic number also gives number of electrons. Electrons are present in shells which participate in chemical reactions and decide chemical properties. Whereas relative atomic mass is the sum of the number of protons and number of neutrons so the number is more important in predicting the chemical properties of elements.

 22. What are the advantages of the Periodic Table?

Ans: In periodic table elements are arranged in a tabular form. So it is easy to remember the properties of elements if the position is known. Also the compounds formed by the elements are predictable if the position of the element is known. Periodic table made it easy and systematic to study chemistry.

 23. Which of the following electronic configuration are wrong and why?

 2,8,2

Ans: From the given electronic configuration, 2,8,9,1 is wrong because in the third shell the maximum number of electrons is 8. The correct electronic configuration is 2,8,8,2.

24. What are ions? What are its two types?

Ans: When one or more electrons are detached from a neutral atom, a positively charged particle is formed and called an ion. Ions may be cations and anions.

25. Show diagrammatically the formation of ${{O}^{2-}}$ ion?

Ans: Atomic number of oxygen is 8 and its electronic configuration is 2,6. In the outermost shell oxygen has 6 electrons. To complete its octet and become stable it needs 2 electrons. By gaining 2 electrons it becomes ${{O}^{2-}}$ ion.

Diagrammatic representation of formation of ${{O}^{2-}}$ ion is as follows:

26. Define isotopes and isobars?

Ans : Isotopes are atoms which have identical atomic numbers but different mass numbers. Examples of isotopes are ${}_{6}^{12}C,{}_{6}^{14}C$.

Isobars are atoms that have different atomic numbers but the same mass number. Examples of isobars are ${}_{18}^{40}Ar,{}_{19}^{40}K$.

Short Answer Questions (3 Marks)

27. For the symbol H, D and T tabulate three subatomic particles found in each of them.

Ans: H represents the hydrogen atom, D represents the deuterium atom and T represents the tritium atom. Three subatomic particles present in each of them is represented as follows:

28. Write the electronic configuration of any one pair of isotopes and isobars.

Ans: Electronic configuration of pairs of isotopes of carbon is ${}_{6}^{12}C,{}_{6}^{14}C$. Isotopes have the same number of electrons and protons.

Electronic configuration of a pair of isobars of argon and calcium is ${}_{18}^{40}Ar,{}_{20}^{40}Ca$.

29. Compare the properties of electrons, protons and neutrons.

Ans: Comparison of electrons, protons and neutrons is as follows:

30. What are the limitations of Rutherford’s model of the atom?

Ans: Rutherford’s model of atom is failed to explain the stability of atom because as per his model electrons revolve around the nucleus and while moving through orbit should emit energy and this energy loss will shrink the orbit and finally the electron would hit the nucleus and thus atom is unstable but it is not true.

31. Define valency by taking examples of silicon and oxygen.

Ans : The valency of electrons is determined by electrons present in the outermost shell of an atom. Electrons present in the outermost shell of an atom are known as the valence electrons. Electrons gain or lose electrons to complete its octet. The valency of silicon is 14 and electronic configuration is 2,8,4. So silicon can gain or lose 4 electrons. So the valency of silicon is +4 or -4.

Atomic number of oxygen is 8 and the electronic configuration is 2,6. To complete its octet oxygen gains 2 electrons hence the valency of oxygen is 2.

32. If bromine atom is available in the form of, say, two isotopes ${}_{35}^{79}Br(49.7%)$ and ${}_{35}^{81}Br(50.3%)$, Calculate the average atomic mass of bromine atom.

Ans: The average atomic mass of bromine is 

$=\dfrac{79\times 49.7+81\times 50.3}{100}$ 

$=\dfrac{3926.3+4074.3}{100}$ 

$=\dfrac{8000.6}{100}$ 

$=80u$ 

Average atomic mass of bromine atoms is 80 u.

33. The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes ${}_{8}^{16}X$ ${}_{8}^{18}X$ and in the sample?

Ans: Average atomic mass of sample is given as

$\dfrac{16X+18\times \left( 100-X \right)}{100}$ 

 $\Rightarrow 16.2=\dfrac{16X+18\times \left( 100-X \right)}{100}$

$\Rightarrow 1620=-2X+1800$

$\Rightarrow 2X=1800-1620$

$\Rightarrow 2X=180$

$\therefore X=90$ 

The percentage of isotopes is ${}_{8}^{16}X(90%)$ and ${}_{8}^{18}X(10%)$.

34. In a gold – foil experiment:

Why did many $\alpha -$ particles pass through the gold foil undeflected?

Ans: Most of the space within the atom was empty so many $\alpha -$ particles passed through the gold foil undeflected.

Why did few $\alpha -$ particles deflect through small angles.

Ans: In a gold foil at center there is a positive charge so few $\alpha -$ particles deflect through small angles.

Why did few $\alpha -$ particles, after striking the gold foil, retrace their path.

Ans : In a gold foil there is a positively charged nucleus which is very tiny so few $\alpha -$ particles, after striking the gold foil, retrace their path.

 Compare the three major particles in atoms with respect to their mass and charge?

Ans: Comparison of three major particles proton, neutron and electron with respect to their mass and charge is as follows:

Inside an atom electron revolves around the nucleus in a circular path. Protons and neutrons are present inside the nucleus.

35. Write an experiment to show cathode rays are deflected by magnetic fields?

Ans: Experiment to show that cathode rays were deflected by magnetic fields is as follows:

First take a discharge tube with fluorescent material inside it.

Place a horse – shoe magnet in the center of the discharge tube.

When cathode rays are produced and travel through the discharge tube, then cathode rays get deflected by the magnetic field of the magnets in the direction of anode. Also they are negatively charged.

The diagram of experiment is as follows:

36. Write the postulates of Bohr theory?

Ans : The postulate of Bohr’s theory is as follows:

An electron revolves around the nucleus in the orbit of an atom in a definite path known as orbits or shells.

Energy of each orbit is fixed.

Energy increases from inner shell to the outer shells i.e. energy for orbit nearest the nucleus is lowest.

If energy is supplied then the electron moves from lower orbit to higher orbit.

37. Explain the variation of atomic radius along a period and down a group.

Ans: The atomic radius of an atom increases when we move down as an extra shell is added. The atomic radius decreases when we move from left to right as the nuclear charge of an element increases.

38. Why metals are electropositive and non-metals are electronegative in nature?

Ans : Metals are electropositive in nature because all metals give away electrons from their outermost shell in order to complete the octet and become stable. So metals become positively charged. Non-metals are electronegative in nature because all non-metals gain electrons in order to complete the octet and become stable. So non-metals become negatively charged.

39. Explain the formation of $A{{l}^{3+}}$ ion and why is it formed?

Ans: Aluminum has an atomic number of 13. The electronic configuration of Al is 2,8,3. It has 3 electrons in the outermost shell and to become stable it needs to complete its octet. In the outermost shell, the maximum number of electrons must be 8. So it is easy to lose 3 electrons and complete the octet. By giving away the 3 outermost electrons it becomes  $A{{l}^{3+}}$ ion.

40. Find the percentage composition of sucrose $\left( {{C}_{12}}{{H}_{22}}{{O}_{11}} \right)$.

Ans: The molecular mass of sucrose $\left( {{C}_{12}}{{H}_{22}}{{O}_{11}} \right)$ is

$\left( {{C}_{12}}{{H}_{22}}{{O}_{11}} \right)=12\times 12+22+11\times 16$

$\left( {{C}_{12}}{{H}_{22}}{{O}_{11}} \right)=144+22+176$

$\left( {{C}_{12}}{{H}_{22}}{{O}_{11}} \right)=342g/mol$

342 g of sucrose contains 144g Carbon, 22 g Hydrogen and 176 g Oxygen.

So 100 g sucrose contains:

$C=\dfrac{100\times 144}{342}=42.11g$ 

\[H=\dfrac{100\times 22}{342}=6.43g\]

$O=\dfrac{100\times 176}{342}=51.46g$

So the percentage composition of sucrose is

$C=42.11%$ 

$H=6.43%$ 

$O=51.46%$.

41. Complete the following table:

Ans: In the given table element is represented as ${}_{Z}^{A}X$.

Here, X is the symbol of element,

Z is the symbol of atomic number which is equal to number of protons,

A is the symbol of mass number which is equal to the sum of the number of protons and the number of neutrons.

By using above information we get the complete table as:

 Calculate the following:

 The number of gram – atoms of oxygen

Ans: Oxygen atoms are represented as ${{O}_{2}}$.  In oxygen 2 gram atoms are present.

 The number of atom of oxygen

Ans : Gram atomic mass of oxygen is $6.023\times {{10}^{23}}atoms$.

16 g of oxygen has $6.023\times {{10}^{23}}atoms$.

So 32 g of oxygen has $\dfrac{6.023\times {{10}^{23}}\times 32}{16}=1.205\times {{10}^{24}}atoms$. 

The number of molecules in 32 g of ozone $\left[ {{O}_{3}} \right]$.

Ans: We know that 48 g of ozone contains $6.023\times {{10}^{23}}molecules$.

So 1 g of ozone contains \[\dfrac{6.023\times {{10}^{23}}}{48}\] molecules.

Thus 32 g of ozone has \[\dfrac{6.023\times {{10}^{23}}\times 32}{48}=4.015\times {{10}^{23}}molecules.\]

 What mass of water will contain the same number of molecules as 8.0 g of ferrous oxide [FeO]?

Ans : We know that the atomic mass of 18 g of water is $6.023\times {{10}^{23}}atoms$.

Ferrous oxide is $56+16=72g$ 

So the atomic mass of 72 g of FeO is $6.023\times {{10}^{23}}atoms$.

Now, 1 g of FeO is \[=\dfrac{6.023\times {{10}^{23}}}{72}\] 

Also, 8 g of FeO is \[=\dfrac{6.023\times {{10}^{23}}\times 8}{72}\].

8 g of FeO is \[=0.669\times {{10}^{23}}\].

Now, 18 g of water is $6.023\times {{10}^{23}}atoms$.

$\dfrac{18}{6.023\times {{10}^{23}}}gms=1\text{ }atom$ 

$\Rightarrow \dfrac{18\times 0.669\times {{10}^{23}}}{6.023\times {{10}^{23}}}gms=0.669\times {{10}^{23}}\text{ }atoms$

Therefore, 2g of water contains \[=0.669\times {{10}^{23}}\].

So 2g of water will contain the same number of molecules as 8 g of ferrous oxide.

Long Answer Questions (5 Marks)

42. How will you find the valency of chlorine, Sulphur and magnesium?

Ans: The valency of electrons is determined by electrons present in the outermost shell of an atom. Electrons present in the outermost shell of an atom are known as the valence electrons. Those electrons determine the valency of that atom.

The atomic number of chlorine is 17 and the electronic configuration is 2,8,7.

Thus chlorine has 7 electrons in the outermost shell and to complete its octet it needs 1 more electron. So the valency of chlorine is one.

The atomic number of Sulphur is 16 and the electronic configuration is 2,8,6.

Thus Sulphur has 6 electrons in the outermost shell and to complete its octet it needs 2 more electrons. So the valency of Sulphur is two.

The atomic number of Magnesium is 12 and the electronic configuration is 2,8,2.

Thus Magnesium has 2 electrons in the outermost shell. It is easy to give away two valence electrons. So the valency of Magnesium is two.

43. Describe Bohr’s model of the atom.

Ans : There are some drawbacks in Rutherford’s atomic model. So to overcome this and to explain the structure of atoms in detail Neil Bohr in 1912 proposed a model of atoms. The postulates of Bohr’s model are given below:

An electron revolves around the nucleus in the orbit of an atom with fixed energy.

Energy of orbits increases from inner shell to the outer shells i.e. energy for orbit nearest the nucleus is lowest.

If energy is supplied then the electron moves from lower orbit to the higher orbit and if an electron jumps from higher orbit (energy level) to the lower orbit (energy level) then energy is emitted as electromagnetic waves.

Each orbit or shell represents an energy level by an integer number as n=1,2,3,….  Such orbits are characterized as K,L,M,N……….. and titled from nucleus side to outwards.

44. Compare all the proposed models of an atom given in this chapter.

Ans: There are three proposed models of an atom are discussed in detail i.e. Thomson’s model, Rutherford’s model and Bohr’s model.

The comparison between the three is given below:

45. Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.

Ans: The following rules are followed for writing the number of electrons in different energy levels or shells:

The maximum number of electrons existing in a shell is given by the formula $2{{n}^{2}}$, where ‘n’ is the orbit number or energy level and is equal to 1,2,3,…

Hence the maximum number of electrons in different shells are as follows:

In the first orbit or also known as K-shell it will be $2\times {{1}^{2}}=2$ (n=1).

In the second orbit or also known as L-shell will be $2\times {{2}^{2}}=8$ (n=2).

In the third orbit or also known as M-shell will be $2\times {{3}^{2}}=18$ (n=3) and so on.

In the outermost shell the maximum number of electrons can be 8.

First inner shells are filled then outer shells are filled. Electrons are not put up in a given shell, unless the inner shells are filled. That

46. Explain following with examples and Give any two uses of isotopes.

Atomic number

Ans: Atomic number of an atom is equal to the number of protons present inside the nucleus of that atom. It is represented by Z.

Mass number

Ans: The atomic mass of an atom is the sum of masses of protons and neutrons present in its nucleus. It is represented by A. For example, the mass number of Carbon is 12 u because it has 6 protons and 6 neutrons in its nucleus.

Ans: Isotopes are atoms which have identical atomic numbers but different mass numbers. Examples of isotopes are ${}_{6}^{12}C,{}_{6}^{14}C$.

Ans : Isobars are atoms that have different atomic numbers but the same mass number. Examples of isobars are ${}_{18}^{40}Ar,{}_{19}^{40}K$. Total number of neutrons is the same in the atoms.

Two uses of isotopes are as follows:

An isotope of uranium is used in nuclear reactors as a fuel.

An isotope of cobalt is used in the treatment of cancer.

47. Complete the following table.

Ans: The complete table is as follows:

Chapter 4 Science Class 9 Important Questions

Chapter 4 structure of the atom is the part of atomic physics. Some of the scientists who have greatly contributed to modern atomic theory by finding actual evidence are John Dalton, J.J. Thompson, Ernest Rutherford, Niels Bohr, James Chadwick and Ernest Schrodinger.

Topics covered under the structure of atom Class 9 important questions are charged particles in matter, the structure of an atom, Thomson’s model of an atom, rutherford model of an atom, Bohr’s model of an atom, neutrons, distribution of electrons in different orbits, valency, atomic number,  mass number, isotopes and isobars. In this chapter, we also get to know about the discovery of electrons and protons  J.J. Thomson and E.Goldstein, respectively. From the mentioned topics many different questions can be framed in Class 9 Science Chapter 4 important questions.

Structure of Atom

It consists of three main particles: protons, electrons, and neutrons. The nucleus of the atom contains protons which are positively charged and neutrons with no charge.  The outermost region of the atoms is called an electron shell and contains an electron, which is a negatively charged particle.

Key Benefits of CBSE Class 9 Science Chapter 4 Important Questions

Here are some of the benefits of referring to Class 9 Science Chapter 4 Important Questions:

Awareness of Key Topics: Practising important questions provides a clear understanding of the crucial topics covered in the chapter.

Skill Development: Solving these questions enhances time management and problem-solving skills across all vital topics.

Understanding Question Formats: Students gain insights into the difficulty levels and various question formats that may appear in exams.

Confidence Boost: Repeated practice instills confidence in students, making them more assured in tackling exam questions.

Versatility in Exam Preparation: Students become well-prepared to handle any type of questions that may arise in the exam.

Students can find the important question of structure of atom Class 9 on Vedantu, which has been prepared by experts to help students with their annual exam preparation. The correct solution to the important questions is given in the PDF. By this, students can save a lot of time in finding the correct answer for the respective question. To know more about this chapter, download the solution of Class 9 Chapter 4 from our site. Chapter 4 has a good weightage in the final exam. By revising the concepts of Chapter 4, you can achieve almost 10 marks from this chapter.

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FAQs on Important Questions for CBSE Class 9 Science Chapter 4 - Structure of the Atom

1. What is the structure of an atom according to Chapter 4 of Class 9 Science?

We learned in Chapter 4 of Class 9 Science that an atom is made up of a nucleus surrounded by electrons and a nucleus made up of protons and neutrons. Electrons have a negative charge, while protons have a positive charge, and neutrons have no charge. The electrons are thought to travel in circular orbits of specified radii corresponding to discrete energy states with the nucleus at the centre in a simplified description of the atomic structure based on the Bohr model. The atom may thus be thought of as being made up of circular shells of electrons, with the lowest shell corresponding to the lowest energy state and the higher level shells having more energy.

2. Why are NCERT Solutions of Chapter 4 of Class 9 Science important?

The NCERT Solutions are a must before every examination and they cumulatively cover all the important concepts. All the NCERT based questions follow a certain pattern and they are extremely essential as this pattern is also adhered to in the examination. Make sure you practice all the NCERT Solutions numerous times to get a good understanding of the concept and further, to leave no scope for error in your exams.

3. What is inside the atom according to Chapter 4 of Class 9 Science notes?

There are a couple of components inside an atom according to Chapter 4 of Class 9 Science. Atoms are the fundamental components of matter. The proton, neutron, and electron are the three subatomic particles that make up the smallest unit of matter. Protons, neutrons, and electrons make up the basic structure of an atom. The mass and charge of the atoms are provided by these fundamental components. The proton and neutron make up the nucleus, with the electron circling around it. Students can learn more about this topic from Vedantu and the study material is absolutely free of cost.

4. What is Z in chemistry according to Chapter 4 of Class 9 Science?

The number of protons in the nucleus of every atom of a chemical element is known as the atomic number or proton number which has the symbol Z. A chemical element's atomic number is the only way to identify it and it makes an element unique. It is the same as the nucleus' charge number. The atomic number is also equivalent to the number of electrons in an uncharged atom.

5. What are neutrons in accordance with Chapter 4 of Class 9 Science?

Chadwick found another subatomic particle with a mass almost equal to that of a proton but no charge. It was given the name neutron later on. Except for hydrogen, all atoms have neutrons in their nuclei. In general, a neutron is denoted by the letter ‘n’. The total of the masses of the protons and neutrons in the nucleus determines the mass of an atom. Neutrons are introduced in the Chapter 4 of Class 9 Science and they are explained thoroughly in the NCERT notes.

CBSE Class 9 Science Important Questions

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Extra Questions for Class 9 Science Chapter 4 Structure of the Atom

Extra questions for Class 9 Science Chapter 4 Structure of the Atom 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.

Structure of the Atom Class 9 Science Extra Questions and Answers

Very short answer questions.

1: Draw the atomic structure of hydrogen atom. Answer:

2: Why are some elements chemically inert? Answer:  Because their outermost shell is completely filled.

3: Why is atom electrically neutral? Answer:  It has same number of protons and electrons, (positive charge = negative charge).

4: What is the charge and mass of a-particles? Answer:  Charge is + 2 Mass is 4 a.m.u.

5: What are valence electrons? Answer:  Electrons present in the outermost shell of an atom are called valence electrons.

6: An atom has atomic number 12, what is its valency and name the element? Answer:  Atomic number = 12 ∴ Protons = Electrons = 12 Electrons Configuration = K L M -2 8 2 ∴ Valency = 2 Element is magnesium.

7: Find the number of neutrons in  27 13 X. Answer:  Mass number = 27 ∴ p + n = 27 p = 13, (Atomic No. = Number of protons) ∴ 13 + n = 27 ∴ n = 14 ∴ Neutron =14

8: Where is the mass of atom is concentrated? Answer:  Mass of an atom is concentrated in nucleus.

9: Name two elements with same number of protons and neutrons? Answer:  Carbon (Protons = Neutrons = 6) Oxygen (Protons = Neutrons = 8)

10: Draw the atomic structure of sodium atom. Answer: 

11: Name the isotope used for treatment of cancer. Answer:  Isotope of cobalt. 12: AZX What does this symbol represent? Answer:  X → Symbol of element A → Mass number Z → Atomic number

13: Can the value of ‘Z’ be same for two different atoms? Answer:  No, (Z = atomic number), two different atoms cannot have same atomic number.

14: Can the value of A’ be same for two different atom? Answer:  Yes, it can be e.g. Ca and Ar has A-40 (i.e., mass number).

Short Answer Type Questions

1: Name the scientist who discovered protons and neutrons in an atoms. Answer:  Protons were discovered by E. Goldstein in 1866 and neutrons were discovered by J, Chadwick in 1932.

2: What is the contribution of Bohr and Bury together in the structure of atom’s explanation? Answer:  Both Bohr and Bury gave the distribution of electrons into different atoms by giving the formula 2n 2 , where n = shell number.

3: Draw the atomic structure of (i) an atom with same number of sub-atomic particles, (ii) an atom with same number of electrons in L and M shell.

Answer:  (i) An atom with same number of sub-atomic particles is He No. of protons = 2 No. of electrons = 2 No. of neutrons = 2

(ii) An atom with L and M shell filled → K L M- 2 8 8

4: What is an octate? Why would atoms want to complete their octate?

Answer:  When the outermost shell of an atom i.e., L, M or N are completely filled with 8 electrons in the shell, it is said an octate. Atoms would want to complete their octate because they want to become stable. 

5: Find the valency of  14 7 N and  35 17 Cl.

Answer:  The atomic number of nitrogen = 7, No. of protons = 7, No. of electrons = 7 Electronic configuration = K L M = 2 5 – Valency = 3 Because either it will gain three electrons or share 3 electrons to complete its octate. The atomic number of chlorine = 17, p = 17, e=17 Electronic configuration = K L M= 2 8 7 Valency = 1 Because it will gain 1 electron to complete its octate. 

8: What are nucleons? What is the name given to those atoms which have same number of nucleons in it?

Answer:  Protons and neutrons present in the nucleus are called nucleons Isobaric elements have same number of nucleons in it.

9: Give the difference between three sub-atomic particles.

Answer:  Three sub-atomic particles are electron, proton and neutron

10. Give the names of three atomic species of hydrogen. Answer:  Three atomic species of hydrogen are:

11: Atomic Mass exists as whole number, why do we write the atomic mass of chlorine as 35.5 u.

Answer:  Chlorine has two isotopes and the mass of an atom is taken as the average mass of all the naturally occurring atoms of that element. This is obtained by knowing the percentage of each isotopic from and then the average mass is calculated Cl = 35 – 75% and Cl = 37 – 25% = 35.5 u

12:  Give difference between isotopes, and isobars. Answer:

13: Number of protons and electrons are same in an atom. Then why is it wrong to say that atomic number of an atom is equal to its number of electrons.

Answer:  Atomic number ≠ Number of electrons, although number of protons = number of electrons because the electron’s number can change in an atom by loss, or gain of it. But the proton’s number remain constant (as it does not take part in loss or gain). 14: An atom is electrically neutral, on loss or gain of electrons why does it become charged?

Answer:  An atom is electrically neutral because of same number of protons and electrons. But it becomes charged, to become stable atom, loses or gains electrons. Hence, Number of protons ≠ Number of electrons If it loses electrons p > e; hence +ve charge is obtained. If it gains electrons e > p; hence -ve charge is obtained. 15: What is valency? Explain different types of valencies. Answer:  The combining capacity of an atom is called its valency. There are 2 types of valencies.

Some atoms also show zero valency when there outermost shell is completely filled. 16:  With the help of an activity in daily life, how can you prove that atoms are divisible. 

Answer:   Activity

• Take a scale, rub it on hair, try to attract a small bit of paper.
• Now divide the bit of paper further into smaller pieces
• Again bring the charged scale near to this pieces of papers.
• You will observe that the bits of paper still get attracted.

Conclusion:  This activity shows that atom contains charges and these charges are opposite in nature which shows the attraction. Hence here scale and paper both are oppositely charged and hence attract each other. Also, every atom has at least one sub-atomic particle.

17: In the structure of an atom why are protons present in the centre and are not pulled outside by the electrons as both are oppositely charged with same unit of charge?

Answer:  Protons are heavy with mass 1 unit and hence are concentrated in the centre   of the atom. The mass of electrons is negligible i.e.1/1800 times less than that of protons. Hence are not able to attract the protons and pull them out of the nucleus, although their charge is of same value. 

18: According to you, among the structure of atom studied which model is correct and why?

Answer:  Bohr’s model of an atom is the best model and is correct because it gives the explanation of nucleons (protons and neutrons) in the centre and how electrons revolve around the nucleons in their discrete, special orbits, so electrons don’t loose/radiate energy and remain bonded in their shell. 

Long Answer Type Questions

1. Give an activity to understand the implications of Rutherford’s a scattering experiment by a gold foil.

Answer:  To understand the implications of Rutherford’s a-particle scattering experiment: Activity:  Let a child stand in front of a wall with his eyes closed. Let him throw stones at the wall from a distance. He will hear sound for each strike of stone on the wall. This is like a nucleus of the atom. But if a blind-folded child has to throw stones at a barbed-wire fence, most of the stones would not hit the fencing and no sound would be heard. This is because there are lots of gap in the fence which allows the stone to pass through them. This is like empty space in an atom through which a-particles will pass through. Based on the above activity and similar reasoning Rutherford concluded the a-particle scattering experiment as: (1) Most of the space inside the atom is empty as a-particles passed through the foil. (2) Very few particles deflected from their path, this show that positive charge occupies less space. (3) A very small fraction of a-particles are deflected by 180°, this shows that all the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.

2: What are isotopes? State its characteristics, give uses of isotopes?

Answer:  Atoms of same element with same atomic number but different mass number are isotopes. Characteristics:  (1) Physical properties of the isotopes are different e.g. mass, density. (2) Chemical properties of the isotopes are same due to same number of electrons. Uses: (1) Uranium isotope is used as a fuel in nuclear reactor (U-235). (2) Cobalt isotope is used for treatment of cancer (Co-60). (3) Iodine isotope is used in the treatment of goitre.

3: Explain Rutherford’s α-particle scattering experiment and give its observation and conclusion drawn.

Answer:   Rutherford’s α-particle scattering experiment: Fast moving α-particles were made to fall on a thin gold foil. Particles have + 2 charge and 4u mass, and considerable amount of energy.

Observations: (1) Most of the α-particles passed straight through the foil. (2) Some of the α-particles were deflected by small angles by the foil. (3) One out of every 12000 particles rebounded.

Conclusion from observation: (1) Most of the space inside the foil is empty. (2) Positive charge of atom occupies very less space. (3) Mass of the atom is concentrated in the centre with all positive charge concentrated in small volume within the atom.

4: Establish the relationship between atomic number, mass number, isotopes, isobars and valency of an atom.

Answer:  Atomic number — Gives the number of protons (Z) Mass number — Gives the number of protons and neutrons (A) Isotopes — When atoms of same element have same number of protons (Z) but different number of a neutrons (s) such atoms are called isotopes. Isobars — When atom of different element have same mass number (A) but different atomic number (Z) such atoms are called isobars. Valency — It is the combining capacity of an atom.

Value Based Questions

1: Aryan could not solve the following question in the group; his group mate explained him and solved his difficulty. The question was as follows: What information do you get from the given figure about the atomic number, mass number and valency of the given atom X’. (a) What is the answer for-the above question? (b) Name the element X’. (c) What value of Aryan’s friend is reflected in this behaviour?

Answer:  (a) The atomic number is 5. The mass number is 11. The valency is 3. (b) The element X’ is boron. (c) Aryan’s friend showed the value of helping and caring nature.

CBSE Expert

Case Study Questions of Class 9 Science PDF Download

Download PDF Case Study Questions of Class 9 Science to prepare for the upcoming CBSE Class 9 Exams Exam 2023-24. 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 .

Case study questions are based on real or hypothetical scenarios that require students to analyze, evaluate, and apply scientific concepts to solve problems or make informed decisions. They often present a detailed context, providing students with the opportunity to demonstrate their understanding of the subject matter beyond basic recall.

Table of Contents

Class 9 Science: Case Study Questions

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.

Chapterwise Case Study Questions of Class 9 Science

• 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

You can find a wide range of solved case studies on cbseexperts, 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.

Class 9 Science Syllabus

Unit I: Matter-Nature and Behaviour

 Definition of matter; solid, liquid, and gas; characteristics – shape, volume, density; change of statementing (absorption of heat), freezing, evaporation (cooling by evaporation), condensation, sublimation.

Nature of matter:  Elements, compounds, and mixtures. Heterogeneous and homogenous mixtures, colloids, and suspensions. Physical and chemical changes (excluding separating the components of a mixture).

Particle nature and their basic units:  Atoms and molecules, Law of Chemical Combination, Chemical formula of common compounds, Atomic and molecular masses.

Structure of atoms:  Electrons, protons and neutrons, Valency, Atomic Number and Mass Number, Isotopes and Isobars.

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).

Unit III: Motio n, 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, 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.

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 (excluding commercial unit 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.

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.

Books for Class 9 Science Exams

Benefits of Case Study Questions

• Enhancing Analytical Skills : Case study questions challenge students to analyze complex scenarios, identify relevant information, and derive meaningful insights. By engaging with these questions, students develop critical analytical skills that are essential for scientific thinking and problem-solving.
• Promoting Critical Thinking : Case study questions encourage students to think critically and evaluate different perspectives. They require students to reason, make logical deductions, and justify their answers with supporting evidence. This process helps in honing their critical thinking abilities, enabling them to approach problems from multiple angles.
• Encouraging Practical Application of Concepts : By presenting real-world or hypothetical situations, case study questions promote the application of scientific concepts in practical scenarios. This application-based approach fosters a deeper understanding of the subject matter and helps students see the relevance of what they learn in the classroom to everyday life.

Case study questions of Class 9 Science provide students with an opportunity to apply their knowledge, enhance analytical skills, and think critically. By understanding the format, benefits, and effective strategies for answering case study questions, students can excel in this form of assessment. While challenges may arise, practicing time management, improving information extraction skills, and enhancing observation abilities will enable students to overcome these obstacles and perform well. Embracing case study questions as a valuable learning tool can contribute to a holistic understanding of scientific concepts and foster problem-solving abilities.

1. What is the purpose of case study questions in Class 9 Science?

Case study questions serve the purpose of evaluating a student’s understanding of scientific concepts, their ability to apply knowledge in real-life situations, and their analytical and critical thinking skills.

2. How can case study questions help improve analytical skills?

Case study questions require students to analyze complex scenarios, identify relevant information, and derive meaningful insights. Regular practice with such questions can significantly enhance analytical skills.

3. Are case study questions difficult to answer?

Case study questions can be challenging due to their comprehensive nature and the need for critical thinking. However, with practice and effective strategies, students can develop the skills necessary to answer them effectively.

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Class 9 Civics Case Study Questions Chapter 4 Working of Institutions

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Case study Questions on Class 9 Social Science Chapter 4 are very important to solve for your exam. Class 9 Social Science Chapter 10 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 Civics Case Study Questions Chapter 4 Working of Institutions

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

In CBSE Class 9 Social 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.

Working of Institutions Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 9 Social Science Chapter 4 Working of Institutions

Case Study 1: The government is responsible for ensuring security to the citizens and providing facilities for education and health to all. It collects taxes and spends the money thus raised on administration, defense, and development programs. It formulates and implements several welfare schemes. Some people have to make decisions on how to go about these activities. Others have to implement these decisions. If disputes arise on these decisions or in their implementation, there should be someone to determine what is right. and what is wrong. It is important that everyone should know who is responsible for doing what. It is also important that these activities keep taking place even if the persons in key positions change. So, to attend to all these tasks, several arrangements are made in all modern democracies. Such arrangements are called institutions. Democracy works well when these institutions perform functions assigned to them. The Constitution of any country lays down basic rules on the powers and functions of each institution. We see several such institutions at work. The Prime Minister and the Cabinet are institutions that take all important policy decisions. The Civil Servants, working together, are responsible for taking steps to implement the ministers’ decisions. Supreme Court is an institution where disputes between citizens and the government are finally settled.

What are the main activities of a government? (a) Responsibility for ensuring security to the citizens (b) Providing education and health facilities (c) Implementing several welfare schemes (d) All of the above

Answer: (d) All of the above

If disputes arise regarding the activities of the government, identify the correct option. I. The Supreme Court should be consulted. II. Parliament will take the decision. III. The Prime Minister will take the decision. Codes (a) Only I (b) Both I and II (c) Only III (d) All to these

Answer: (a) Only I

Which of the following is/are regarded as institutions in democracy? (a) The Prime Minister and the Cabinet (b) The Civil Servants (c) The Supreme Court (d) All of these

Which of the following is considered as reason for delay in the decision making procedure of democracy? (a) Working with institutions is not easy. (b) Rules and regulations of institutions bind the hands of leaders. (c) It involves meetings, committees and routines. (d) All of the above

Which of the following can be regarded as better option instead of institutions in democracy? (a) One person takes all decisions without any rules, procedures and meeting. (b) A group of people take all decisions. (c) Judiciary can take all decisions. (d) None of the above

Answer: (d) None of the above

Which of the following is/are correct regarding the institutions in democracy? (a) Institutions make it difficult to have a good decision taken very quickly. (b) Institutions make it equally difficult rush through a bad decision. (c) Both (a) and (b) (d) None of these

Case Study 2: In a democracy, institutions play a crucial role in ensuring the smooth functioning of the government and the protection of citizens’ rights. The three main institutions in India’s democratic setup are the Legislature, the Executive, and the Judiciary. The Legislature consists of elected representatives who make laws and debate issues in the Parliament and State Legislative Assemblies. The Executive comprises the President, the Prime Minister, and the Council of Ministers, who are responsible for implementing laws and policies. The Judiciary, headed by the Supreme Court, is responsible for interpreting and upholding the Constitution, resolving disputes, and safeguarding the rights of citizens. These institutions work independently of each other but maintain a system of checks and balances to prevent the abuse of power. The working of these institutions is essential for the proper functioning of democracy and the protection of the rights and interests of the people.

What are the three main institutions in India’s democratic setup? a) Judiciary, Parliament, and Council of Ministers b) Legislature, Executive, and Judiciary c) President, Prime Minister, and Cabinet d) Rajya Sabha, Lok Sabha, and State Legislative Assemblies

Answer: b) Legislature, Executive, and Judiciary

What is the role of the Legislature in a democracy? a) Implementing laws and policies b) Interpreting and upholding the Constitution c) Making laws and debating issues d) Resolving disputes and safeguarding citizens’ rights

Answer: c) Making laws and debating issues

Who is responsible for implementing laws and policies in India? a) President, Prime Minister, and Council of Ministers b) Supreme Court and its judges c) Members of Parliament and State Legislative Assemblies d) Election Commission of India

Answer: a) President, Prime Minister, and Council of Ministers

Which institution is responsible for interpreting and upholding the Constitution? a) Parliament b) President c) Supreme Court d) Election Commission of India

Answer: c) Supreme Court

How do the institutions of democracy maintain a system of checks and balances? a) By implementing laws and policies b) By interpreting and upholding the Constitution c) By making laws and debating issues d) By working independently but overseeing each other’s actions

Answer: d) By working independently but overseeing each other’s actions

Hope the information shed above regarding Case Study and Passage Based Questions for Class 9 Social Science Chapter 4 Working of Institutions with Answers Pdf free download has been useful to an extent. If you have any other queries about CBSE Class 9 Social Science Working of Institutions Case Study and Passage Based Questions with Answers, feel free to comment below so that we can revert back to us at the earliest possible By Team Study Rate

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Case Study Questions Class 9 Science The Fundamental Unit of Life

Case study questions class 9 science chapter 5 the fundamental unit of life.

CBSE Class 9 Case Study Questions Science The Fundamental Unit of Life. Important Case Study Questions for Class 9 Exam. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions The Fundamental Unit of Life.

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

CBSE Case Study Questions Class 9 Science – The Fundamental Unit of Life

All living Organisms are made up of cells and these cells perform all the functions essential for the survival of the Organism eg. Respiration, digestion, excretion etc. In Unicellular organisms, a single cell carries out all these functions and in multicellular organisms different group of cells carry out different functions.

Cells were first discovered by Robert Hooke in 1665. He observed the cells in a cork slice with the help of a primitive microscope. Leeuwenhoek (1674), with the improved microscope, discovered the free living cells in pond water for the first time. It was Robert Brown in 1831 who discovered the nucleus in the cell. Purkinje in 1839 coined the term ‘protoplasm’ for the fluid substance of the cell.

(1) Who discovered the cell?

(a) Robert Hooke

(b) Leeuwenhoek

(c) Robert Brown

(d) T. Schwann

(2) Who discovered the nucleus in the cell?

(3) Who coined the term ‘Protoplasm’?

(d) Purkinje

(4) What is protoplasm?

(a) Unit of life

(b) Cell organelle

(c) Fluid substance of the cell.

(d) Cytoplasm

(5) Which of these statement is true about the cell?

(a) All organism are made up of cell

(b) Cell is the basic unit of life

(c) Cell is responsible for different metabolic functions

(d) All above

The cell theory, that all the plants and animals are composed of cells and that the cell is the basic unit of life, was presented by two biologists, German zoologist Schleiden (1838) and British zoologist Schwann (1839). The cell theory was further expanded by Virchow (1855) by suggesting that all cells arise from pre-existing cells. With the discovery of the electron microscope in 1940, it was possible to observe and understand the complex structure of the cell and its various organelles.

(1) Theodore Schwann was a _____

(a) British zoologist

(b) German zoologist

(c) British botanist

(d) German botanist

(2) Matthias Schleiden was a _____

(a) German zoologist

(b) British zoologist

(c) German botanist

(d) British botanist

(3) Which of these scientists formulated the cell theory?

(a) Schleiden and Schwann

(b) Rudolf Virchow

(c) Robert Koch

(d) Antony Von Leeuwenhoek

(4) Which scientist was the first to explain that new cells arise from pre-existing cells?

(a) Antony Von Leeuwenhoek

(b) Matthias Schleiden

(c) Rudolph Virchow

(d) Theodore Schwann

(5) Which of these scientists did not contribute to the cell theory?

(a) Robert Koch

(c) Theodore Schwann

(d) Rudolph Virchow

Plasma membrane or Cell membrane is the outermost covering of the cell that separates the contents of the cell from its external environment. The plasma membrane is flexible and is made up of organic molecules called lipids and proteins. The flexibility of the cell membrane also enables the cell to engulf in food and other material from its external environment. Such processes are known as endocytosis.The plasma membrane allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. The cell membrane, therefore, is called a selectively permeable membrane.

Some substances like carbon dioxide or oxygen can move across the cell membrane by a process called diffusion. There is spontaneous movement of a substance from a region of high concentration to a region where its concentration is low. Similar thing happens in cells – some substance like CO2 (carbon dioxide is cellular waste and requires to be excreted out by the cell) accumulates in high concentrations inside the cell. In the cell’s external environment, the concentration of CO2 is low as compared to that inside the cell. As soon as there is a difference of concentration of CO2 inside and outside a cell, CO2 moves out of the cell, from a region of high concentration, to a region of low concentration outside the cell by the process of diffusion.

Water obeys the law of diffusion. The movement of water molecules through such a selectively permeable membrane is called osmosis. The movement of water across the plasma membrane is also affected by the amount of substance dissolved in water. Thus, osmosis is the net diffusion of water across a selectively permeable membrane toward a higher solute concentration.

(1) The plasma membrane is made up of ___________

(a) Proteins

(c) Proteins and Lipids (Lipoproteins)

(d) none of above

(2) Which of the following substance is known as cellular waste?

(b) Nitrogen

(c) Carbon dioxide

(d) None of above

(3) The movement of a substance from the region of higher concentration to the region where its concentration is lower is called as _____________

(a) Osmosis

(b) Diffusion

(c) Excretion of CO2 (carbon dioxide)

(4) Why cell membrane is known as selectively permeable membrane?

(5) What is mean by diffusion?

(6) Define Osmosis.

(d) Cell membrane allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. Hence it is called as selectively permeable membrane.

(e) It is spontaneous movement of a substance from a region of high concentration to a region where its concentration is low. For example, some substances like carbon dioxide or oxygen can move across the cell membrane by a process called diffusion.

Plant cells, in addition to the plasma membrane, have another rigid outer covering called the cell wall. The cell wall lies outside the plasma membrane. The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants. When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.

(1) Which of the following is the main constituent of cell wall?

(c) Lipoproteins

(d) Cellulose

(2) Which of the following is outer most covering of the plant cell?

(a) Cell membrane

(b) Plasma membrane

(c) Cell wall

(3) Choose the correct set of statements from the following.

Statement 1 – Cell wall lies outside the plasma membrane.

Statement 2 – Cell wall is mainly composed of cellulose.

Statement 3 – Cellulose is a complex substance and provides structural strength to plants.

Statement 4 – Cell wall lies outside the plasma membrane.

(a) Statement 1 & 3

(b) Statement 1 & 2

(c) Statement 3 & 4

(d) All statement are correct

(4) What is mean by plasmolysis?

(5) What is the reason behind structural strength of plant cell?

(4) When living plant cell loses water through osmosis there is contraction of the contents of the cell away from the cell wall. This phenomenon is called as plasmolysis.

(5) The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants.

Every cell has a membrane around it to keep its own contents separate from the external environment. Large and complex cells, including cells from multicellular organisms, need a lot of chemical activities to support their complicated structure and function. To keep these activities of different kinds separate from each other, these cells use membrane-bound little structures within themselves. The cytoplasm is the jelly like fluid content inside the plasma membrane which contains many specialised cell organelles. Such as Endoplasmic Reticulum, Golgi apparatus, Lysosomes, Ribosomes, Nucleus, Chloroplast, Mitochondria and Plastids.Each of these organelles performs a specific function for the cell. Some of these organelles are visible only with an electron microscope. They are important because they carry out some very crucial functions in cells.

(1) Identify the statement which is true for cells.

Statement 1 – Some cell organelles are visible only with an electron microscope.

Statement 2 – Cytoplasm is jelly like fluid present inside the cell.

Statement 3 – Cell organelles perform all the functions in cell.

Statement 4 – Every cell has a membrane around it to keep its own contents separate from the external environment.

(b) Statement 2 & 4

(c) Statement 1 & 4

(d) All statement are true.

(2) A suitable term for the various components of cells is ________

(b) cell organelles

(c) chromosomes

(3) The jelly-like fluid substance present in cells is called __________

(a) Protoplasm

(b) Chromosome

(c) Chloroplast

(4) What is cell organelles?

(5) Enlist the any five cell organelles.

(4) Cell organelles are the specialized organelles present with in the cells these organelles are involved in carrying out essential functions.

(5) Endoplasmic Reticulum, Golgi apparatus, Lysosomes, Ribosomes, Nucleus, Chloroplast, Mitochondria and Plastids.

The endoplasmic reticulum is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags (vesicles). It is discovered by Porter and Thompson.  The ER membrane is similar in structure to the plasma membrane. There are two types of ER– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). RER looks rough under a microscope because it has particles called ribosomes attached to its surface. The ribosomes, which are present in all active cells, are the sites of protein manufacture. The manufactured proteins are then sent to various places in the cell depending on need, using the ER. The SER helps in the manufacture of fat molecules, or lipids, important for cell function. Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis. Some other proteins and lipids function as enzymes and hormones. Although the ER varies greatly in appearance in different cells, it always forms a network system.

(1) Who discovered endoplasmic reticulum?

(a) Porter and Thompson

(b) Robert Brown

(c) Robert Hooke

(d) Koshland

(2) Which are the components of endoplasmic reticulum__________

(a) Cisternae, tubules and vesicles.

(b) Cisternae, chromatids and vacuoles

(c) Both a and b

(d) None of the above

(3) Endoplasmic reticulum membrane which is associated with ribosomes is called_______

(a) ER lumen

(b) Smooth endoplasmic reticulum

(c) Rough endoplasmic reticulum

(d) Endosome

(4) Enlist the types of Endoplasmic Reticulum.

(5) Define membrane biogenesis?

(4) Smooth endoplasmic reticulum and Rough endoplasmic reticulum

(5) The SER helps in the manufacture of fat molecules, or lipids, important for cell function. Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis.

The Golgi apparatus, first described by Camilo Golgi, consists of a system of membrane-bound vesicles (flattened sacs) arranged approximately parallel to each other in stacks called cisterns. These membranes often have connections with the membranes of ER and therefore constitute another portion of a complex cellular membrane system. The material synthesised near the ER is packaged and dispatched to various targets inside and outside the cell through the Golgi apparatus. Its functions include the storage, modification and packaging of products in vesicles. In some cases, complex sugars may be made from simple sugars in the Golgi apparatus. The Golgi apparatus is also involved in the formation of lysosomes

(d) Camilo Golgi

(2) A system of membrane-bound flattened sacs arranged approximately parallel to each other in stacks are called as _________

(a) Cisterns

(b) Vesicles

(c) Golgi complex

(d) Vacuoles

(3) Membrane bound flattened sacs is termed as _________

(4) Enlist the function of Golgi apparatus.

(5) Name the cell organelles which is involved in the formation of lysosomes?

(4) Functions of Golgi apparatus:

• Storage, modification and packaging of products
• Involved in formation of lysosomes

(5) Golgi apparatus

It’s a suggestion that tries to give all the questions in mcq types in case/paragraph-based questions or if you are putting question-based kindly put only very short answer types questions like one word or one sentence it’s more helpful to all. Rest it’s really good information and provides ideas to us.

Ok Dibya, We will design this page

tomorrow is my science final papper. this case study is come in my papper than i am very happy.

This very helpful casebased questions Thanku for this

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