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    NCERT Solutions Class 9 Science Chapter 3 Atoms And Molecules

    NCERT Solutions Class 9 Science Chapter 3 Atoms And Molecules prepared by expert teachers at BYJU'S according to the 2022-23 syllabus of the CBSE exams. Click here to get Class 9 Science NCERT Solutions Chapter 3 Atoms And Molecules.

    NCERT SolutionsNCERT Class 9NCERT 9 ScienceChapter 3: Atoms And Molecules

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    NCERT Solutions for Class 9 Science Chapter 3- Atoms and Molecules

    NCERT Solutions for Class 9 Science Chapter 3- Atoms and Molecules NCERT Solutions for Class 9 Science Chapter 3 – CBSE Get Free PDF

    NCERT Solutions for Class 9 Science Chapter 3- Atoms and Molecules is a detailed study material prepared by experts. It provides answers to the questions given in the textbook. NCERT Solutions are very helpful for a better understanding of the concepts and self-analysis.

    Questions from all the topics are covered in the solutions. Everything is presented in a way that students can easily understand. It will help them score well in the CBSE examination. The answers to all kinds of long and short questions, MCQs, tricks and tips are provided in the NCERT Solutions for Class 9 Science. Try solving the questions after completing the entire syllabus and overcome the shortcomings before the CBSE exams arrive.

    The chapter Atoms and Molecules form the basis of the upcoming chapters, therefore, it should be dealt with thoroughly. The questions and solutions will help the students clarify all their doubts related to the topic.

    The NCERT Solutions for Class 9 carries all the important questions and answers for all the subjects and chapters. The students can refer to these solutions to excel in the CBSE examinations.

    Chapter 3 Atoms And Molecules

    Download PDF of NCERT Solutions for Class 9 Science Chapter 3- Atoms and Molecules

    Access Answers of Science NCERT Class 9 Chapter 3 – Atoms and Molecules (All in text and Exercise Questions solved)

    Class 9 Science Chapter 3 Exercise-3.1 Questions with Answer

    Exercise-3.1 Page: 32

    1. In a reaction, 5.3g of sodium carbonate reacted with 6 g of acetic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium acetate. Show that these observations are in agreement with the law of conservation of mass.

    Sodium carbonate + acetic acid → Sodium acetate + carbon dioxide +  water

    Solution:

    Sodium carbonate + acetic acid → Sodium acetate + carbon dioxide +  water

    5.3g                             6g                 8.2g     2.2g      0.9g

    As per the law of conservation of mass, the total mass of reactants must be equal to the total mass of

    products

    As per the above reaction, LHS = RHS    i.e., 5.3g + 6g = 2.2g + 0.9 g + 8.2 g = 11.3 g

    Hence the observations are in agreement with the law of conservation of mass.

    2. Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

    Solution:

    We know hydrogen and water mix in the ratio 1: 8.

    For every 1g of hydrogen, it is 8g of oxygen.

    Therefore, for 3g of hydrogen, the quantity of oxygen = 3 x 8 = 24g

    Hence, 24g of oxygen would be required for the complete reaction with 3g of hydrogen gas.

    3. Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?

    Solution:

    The relative number and types of atoms are constant in a given composition,’ says Dalton’s atomic theory, which is based on the rule of conservation of mass.

    “Atoms cannot be created nor be destroyed in a chemical reaction”.

    4. Which postulate of Dalton’s atomic theory can explain the law of definite proportions?

    Solution:

    The postulate of Dalton’s atomic theory that can explain the law of definite proportions is – the

    relative number and kinds of atoms are equal in given compounds.

    Exercise-3.2 Page: 35

    1. Define the atomic mass unit?

    Solution:

    An atomic mass unit is a unit of mass used to express weights of atoms and molecules where one

    atomic mass is equal to 1/12th the mass of one carbon-12 atom.

    2. Why is it not possible to see an atom with naked eyes?

    Solution:

    Firstly, atoms are miniscule in nature, measured in nanometers. Secondly, except for atoms of noble

    gasses, they do not exist independently. Hence, an atom cannot be visible to the naked eyes.

    Exercise-3.3-3.4 Page: 39

    1. Write down the formulae of(i) sodium oxide(ii) aluminium chloride(iii) sodium sulphide(iv) magnesium hydroxide

    Solution:

    The following are the formulae:

    (i) sodium oxide – Na2O

    (ii) aluminium chloride – AlCl3

    (iii) sodium sulphide – Na2S

    (iv) magnesium hydroxide – Mg (OH)2

    2. Write down the names of compounds represented by the following formulae:(i) Al2(SO4)3(ii) CaCl2(iii) K2SO4(iv) KNO3(v) CaCO3.

    Solution:

    Listed below are the names of the compounds for each of the following formulae

    (i) Al2(SO4)3 – Aluminium sulphate

    (ii) CaCl2 – Calcium chloride

    (iii) K2SO4 – Potassium sulphate

    (iv) KNO3 – Potassium nitrate

    स्रोत : byjus.com

    NCERT Solutions For Class 9 Science Chapter 3 Atoms and Molecules

    Chapter-wise NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules (Chemistry) solved by Expert Teachers as per NCERT (CBSE) Book guidelines. CBSE Class 9 Chemistry Chapter 3 Atoms and Molecules Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks.

    NCERT Solutions For Class 9 Science Chapter 3 Atoms and Molecules

    NCERT Solutions Class 9 Science Chapter 3 Atoms and Molecules – Here are all the NCERT solutions for Class 9 Science Chapter 3. This solution contains questions, answers, images, step by step explanations of the complete Chapter 3 titled Atoms and Molecules of Science taught in class 9. If you are a student of class 9 who is using NCERT Textbook to study Science, then you must come across Chapter 3 Atoms and Molecules. After you have studied lesson, you must be looking for answers of its questions. Here you can get complete NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules in one place. For a better understanding of this chapter, you should also see Chapter 3 Atoms and Molecules Class 9 notes , Science.

    NCERT Solutions For Class 9 Science Chapter 3 Atoms and Molecules

    Topics and Sub Topics in Class 9 Science Chapter 3 Atoms and Molecules:

    Atoms and Molecules

    Laws of Chemical Combination

    What is an Atom? What is a Molecule?

    Writing Chemical Formulae

    Molecular Mass and Mole Concept

    These solutions are part of NCERT Solutions for Class 9 Science. Here we have given Class 9 NCERT Science Text book Solutions for Chapter 1 matter in our Surroundings.

    IN-TEXT QUESTIONS SOLVEDNCERT Textbook for Class 9 Science – Page 32Question 1. In a reaction 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass carbonate. Answer.

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    CBSE Class 9 Science Chapter 3 IN-TEXT QUESTIONS SOLVEDClass 9 Science NCERT Textbook Page 32Question 1. In a reaction 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium etkanoate. Show that these observations are in agreement with the law of conservation of mass carbonate. Answer:

    Question 2. Hydrogen and oxygen combine in the ratio of 1 : 8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas? Answer: Ratio of H : O by mass in water is:

    Hydrogen : Oxygen —> H2O

    ∴ 1 : 8 = 3 : x x = 8 x 3 x = 24 g

    ∴ 24 g of oxygen gas would be required to react completely with 3 g of hydrogen gas.

    Formulae Handbook for Class 9 Maths and ScienceEducational Loans in India

    Question 3. Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass? Answer: The postulate of Dalton’s atomic theory that is the result of the law of conservation of mass is—the relative number and kinds of atoms are constant in a given compound. Atoms cannot be created nor destroyed in a chemical reaction.Question 4. Which postulate of Dalton’s atomic theory can explain the law of definite proportions? Answer: The relative number and kinds of atoms are constant in a given compound.Class 9 Science NCERT Textbook Page 35Question 1. Define the atomic mass unit. Answer: One atomic mass unit is equal to exactly one-twelfth (1/12th) the mass of one atom of carbon-12. The relative atomic masses of all elements have been found with respect to an atom of carbon-12.Question 2. Why is it not possible to see an atom with naked eyes? Answer: Atom is too small to be seen with naked eyes. It is measured in nanometres.

    1 m = 109 nm

    NCERT Textbook Questions – Page 39Question 1. Write down the formulae of (i) Sodium oxide (ii) Aluminium chloride (iii) Sodium sulphide (iv) Magnesium hydroxide Answer: The formulae are

    Question 2. What is meant by the term chemical formula? Answer: The chemical formula of the compound is a symbolic representation of its composition, e.g., chemical formula of sodium chloride is NaCl.

    स्रोत : www.learncbse.in

    NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules

    NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules

    NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules

    24 May, 2021

    NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules

    You will find NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules that are accurate and detailed through which you can prepare your own answers by taking help. These NCERT Solutions are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics. Chapter 3 Class 9 Science NCERT Solutions will give good experience and provide opportunities to learn new things.

    You can figure out the latest marking scheme and prepare your answers as per the demand. Chapter 3 Atoms and Molecules NCERT Questions and Answers help in building a great foundation of concepts and make easy for the students to understand basics. Students can cross check their answers and also whether they learned it properly or not.

    NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules

    These Class 9 Science NCERT Solutions will make you well versed in variety of topics and help students in performing exceptionally well in their CBSE board exams. These NCERT Solutions are curated by the experts in a comprehensive which can be helpful in clearing your doubts instantly. It will be useful in expanding student's horizon as it cover variety of questions.

    Study Reference for Class 9 Chapter 3 Atoms and Molecules

    Revision Notes for Chapter 3 Atoms and MoleculesExtra Questions for Chapter 3 Atoms and MoleculesMCQ Questions for Chapter 3 Atoms and Molecules

    In Text Questions Page No: 32

    1. In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass.

    Sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water

    Answer

    In the given reaction, sodium carbonate reacts with ethanoic acid to produce sodium ethanoate, carbon dioxide, and water.

    Sodium Carbonate + Ethanoic acid → sodium ethanoate + carbon dioxide + water

    Mass of sodium carbonate = 5.3 g (Given)

    Mass of ethanoic acid = 6 g (Given)

    Mass of sodium ethanoate = 8.2 g (Given)

    Mass of carbon dioxide = 2.2 g (Given)

    Mass of water = 0.9 g (Given)

    Now, total mass before the reaction = (5.3 + 6) g

    = 11.3 g

    And, total mass after the reaction = (8.2 + 2.2 + 0.9) g

    = 11.3 g

    ∴ Total mass before the reaction = Total mass after the reaction

    Hence, the given observations are in agreement with the law of conservation of mass.

    Page No: 33

    2. Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

    Answer

    It is given that the ratio of hydrogen and oxygen by mass to form water is 1:8.

    Then, the mass of oxygen gas required to react completely with 1 g of hydrogen gas is 8 g.

    Therefore, the mass of oxygen gas required to react completely with 3 g of hydrogen gas is 8 × 3 g = 24 g.

    3. Which postulate of Dalton's atomic theory is the result of the law of conservation of mass?

    Answer

    The postulate of Dalton :"Atoms are indivisible particles, which can not be created or destroyed in a chemical reaction" is the result of the law of conservation of mass.

    4. Which postulate of Dalton's atomic theory can explain the law of definite proportions?

    Answer

    The postulate of Dalton, “The relative number and kinds of atoms are constant in a given compound”, can explain the law of definite proportions.

    Page No: 35

    1. Define atomic mass unit.

    Answer

    Mass unit equal to exactly one-twelfth the mass of one atom of carbon-12 is called one atomic mass unit. It is written as 'u'.

    2. Why is it not possible to see an atom with naked eyes?

    Answer

    The size of an atom is so small that it is not possible to see it with naked eyes. Also, the atom of an element does not exist independently.

    Page No: 39

    1. Write down the formulae of

    (i) sodium oxide ► Na2O

    (ii) aluminium chloride

    ► AlCl3

    (iii) sodium sulphide

    ► Na2S

    (iv) magnesium hydroxide

    ► Mg(OH)2

    2. Write down the names of compounds represented by the following formulae:

    (i) Al2(SO4)3

    ► Aluminium sulphate

    (ii) CaCl2 ► Calcium chloride (iii) K2SO4

    ► Potassium sulphate

    (iv) KNO3 ► Potassium nitrate (v) CaCO3 ► Calcium carbonate

    3. What is meant by the term chemical formula?

    Answer

    The chemical formula of a compound is a symbolic representation of its composition.

    4. How many atoms are present in a

    (i) H2S molecule and

    (ii) PO43-ion?

    Answer

    (i) In an H2S molecule, three atoms are present; two of hydrogen and one of sulphur.

    (ii) In a PO43-ion, five atoms are present; one of phosphorus and four of oxygen.

    Page No: 40

    1. Calculate the molecular masses of H2, O2, Cl2, CO2, CH4, C2H6, C2H4, NH3, CH3OH.

    स्रोत : www.studyrankers.com

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