NCERT solutions for Science Class 9 chapter 3 - Atoms and Molecules [Latest edition]

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Solutions for Chapter 3: Atoms and Molecules

Below listed, you can find solutions for Chapter 3 of CBSE NCERT for Science Class 9.


Intext QuestionsIntext QuestionsIntext QuestionsIntext QuestionsIntext QuestionsExercises
Intext Questions [Pages 32 - 33]

NCERT solutions for Science Class 9 Chapter 3 Atoms and Molecules Intext Questions [Pages 32 - 33]

Intext Questions | Q 1 | Page 32

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

Intext Questions | Q 2 | Page 33

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?

Intext Questions | Q 3 | Page 33

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

Intext Questions | Q 4 | Page 33

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

Intext Questions [Pages 35 - 39]

NCERT solutions for Science Class 9 Chapter 3 Atoms and Molecules Intext Questions [Pages 35 - 39]

Intext Questions | Q 1 | Page 35

Define atomic mass unit.

Intext Questions | Q 2 | Page 35

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

Intext Questions | Q 4.2 | Page 39

How many atoms are present in a PO43− ion?

Intext Questions [Pages 39 - 23]

NCERT solutions for Science Class 9 Chapter 3 Atoms and Molecules Intext Questions [Pages 39 - 23]

Intext Questions | Q 1.1 | Page 39

Write down the formulae of sodium oxide.

Intext Questions | Q 1.2 | Page 39

Write down the formulae of aluminium chloride.

Intext Questions | Q 1.3 | Page 39

Write down the formulae of sodium sulphide.

Intext Questions | Q 1.4 | Page 39

Write down the formulae of magnesium hydroxide.

Intext Questions | Q 2.1 | Page 39

Write down the name of compound represented by the following formulae:- Al2(SO4)3

Intext Questions | Q 2.2 | Page 39

Write down the name of compound represented by the following formulae:- CaCl2

Intext Questions | Q 2.3 | Page 39

Write down the name of compound represented by the following formulae:-

K2SO4

Intext Questions | Q 2.4 | Page 39

Write down the name of compound represented by the following formulae:-KNO3

Intext Questions | Q 2.5 | Page 39

Write down the name of compound represented by the following formulae:- CaCO3

Intext Questions | Q 3 | Page 39

What is meant by the term chemical formula?

Intext Questions | Q 4.1 | Page 39

How many atoms are present in a H2S molecule?

Intext Questions | Q 4. (ii) | Page 39

How many atoms are present in a PO4 3– ion?

Intext Questions | Q 35. (b) | Page 23

Express each of the following in kilograms

58.34 g

Intext Questions [Page 40]

NCERT solutions for Science Class 9 Chapter 3 Atoms and Molecules Intext Questions [Page 40]

Intext Questions | Q 1.1 | Page 40

Calculate the molecular masses of H2.

Intext Questions | Q 1.2 | Page 40

Calculate the molecular masses of O2.

Intext Questions | Q 1.3 | Page 40

Calculate the molecular masses of Cl2.

Intext Questions | Q 1.4 | Page 40

Calculate the molecular masses of CO2.

Intext Questions | Q 1.5 | Page 40

Calculate the molecular masses of CH4.

Intext Questions | Q 1.6 | Page 40

Calculate the molecular masses of C2H6.

Intext Questions | Q 1.7 | Page 40

Calculate the molecular masses of C2H4.

Intext Questions | Q 1.8 | Page 40

Calculate the molecular masses of NH3.

Intext Questions | Q 1.9 | Page 40

Calculate the molecular masses of CH3OH.

Intext Questions | Q 2.1 | Page 40

Calculate the formula unit masses of ZnO, given atomic masses of Zn = 65 u and O = 16 u.

Intext Questions | Q 2.2 | Page 40

Calculate the formula unit masses of Na2O, given atomic masses of Na = 23 u and O = 16 u.

Intext Questions | Q 2.3 | Page 40

Calculate the formula unit masses of K2CO3, given atomic masses of K = 39 u, C = 12 u, and O = 16 u.

Intext Questions [Page 42]

NCERT solutions for Science Class 9 Chapter 3 Atoms and Molecules Intext Questions [Page 42]

Intext Questions | Q 1 | Page 42

If one mole of carbon atoms weighs 12 gram, what is the mass (in gram) of 1 atom of carbon?

Intext Questions | Q 2 | Page 42

Which has more number of atoms, 100 grams of sodium or 100 grams of iron (given, atomic mass of Na = 23 u, Fe = 56 u)?

Exercises [Pages 43 - 44]

NCERT solutions for Science Class 9 Chapter 3 Atoms and Molecules Exercises [Pages 43 - 44]

Exercises | Q 1 | Page 43

A 0.24 g sample of compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. Calculate the percentage composition of the compound by weight.

Exercises | Q 2 | Page 43

When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combinations will govern your answer?

Exercises | Q 3 | Page 44

What are polyatomic ions? Give examples?

Exercises | Q 4.1 | Page 44

Write the chemical formulae of the Magnesium chloride.

Exercises | Q 4.2 | Page 44

Write the chemical formulae of the Calcium oxide.

Exercises | Q 4.3 | Page 44

Write the chemical formulae of the Copper nitrate.

Exercises | Q 4.5 | Page 44

Write the chemical formulae of the Calcium carbonate.

Exercises | Q 5.1 | Page 44

Give the names of the elements present in the following compound: Quick lime

Exercises | Q 5.2 | Page 44

Give the names of the elements present in the following compound: Hydrogen bromide

Exercises | Q 5.3 | Page 44

Give the names of the elements present in the following compound: Baking powder

Exercises | Q 5.4 | Page 44

Give the names of the elements present in the following compound: Potassium sulphate

Exercises | Q 6.1 | Page 44

Calculate the molar mass of the following substance: Ethyne, C2H2

Exercises | Q 6.2 | Page 44

Calculate the molar mass of the following substance: Sulphur molecule, S8

Exercises | Q 6.3 | Page 44

Calculate the molar mass of the following substance

Phosphorus molecule, P4 (atomic mass of phosphorus = 31)

Exercises | Q 6.4 | Page 44

Calculate the molar mass of the following substance: Hydrochloric acid, HCl

Exercises | Q 6.5 | Page 44

Calculate the molar mass of the following substance: Nitric acid, HNO3

Exercises | Q 7.1 | Page 44

What is the mass of 1 mole of nitrogen atoms?

Exercises | Q 7.2 | Page 44

What is the mass of 4 moles of aluminium atoms (Atomic mass of aluminium = 27)?

Exercises | Q 7.3 | Page 44

What is the mass of 10 moles of sodium sulphite (Na2SO3)?

Exercises | Q 8.1 | Page 44

Convert into mole.

12 g of oxygen gas

Exercises | Q 8.2 | Page 44

Convert into mole.

20 g of water

Exercises | Q 8.3 | Page 44

Convert into mole.

22 g of carbon dioxide

Exercises | Q 9.1 | Page 44

What is the mass of 0.2 mole of oxygen atoms?

Exercises | Q 9.2 | Page 44

What is the mass of 0.5 mole of water molecules?

Exercises | Q 10 | Page 44

Calculate the number of molecules of sulphur (S8) present in 16 g of solid sulphur.

Exercises | Q 11 | Page 44

Calculate the number of aluminium ions present in 0.051 g of aluminium oxide.

(Hint: The mass of an ion is the same as that of an atom of the same element. Atomic mass of Al = 27 u)

Solutions for Chapter 3: Atoms and Molecules

Intext QuestionsIntext QuestionsIntext QuestionsIntext QuestionsIntext QuestionsExercises

NCERT solutions for Science Class 9 chapter 3 - Atoms and Molecules

Shaalaa.com has the CBSE Mathematics Science Class 9 CBSE solutions in a manner that help students grasp basic concepts better and faster. The detailed, step-by-step solutions will help you understand the concepts better and clarify any confusion. NCERT solutions for Mathematics Science Class 9 CBSE 3 (Atoms and Molecules) include all questions with answers and detailed explanations. This will clear students' doubts about questions and improve their application skills while preparing for board exams.

Further, we at Shaalaa.com provide such solutions so students can prepare for written exams. NCERT textbook solutions can be a core help for self-study and provide excellent self-help guidance for students.

Concepts covered in Science Class 9 chapter 3 Atoms and Molecules are Laws of Chemical Combination, History of Atom, Law of Conservation of Mass, Law of Constant Proportions (Law of Definite Proportions), Dalton’s atomic theory, Atoms: Building Blocks of Matter, Symbols Used to Represent Atoms of Different Elements, Atomic Mass, Relative Atomic Mass (RAM), Molecules, Classification of Molecules, Difference Between Atoms and Molecules, Ions (Radicals) and Its Types, Chemical Formula or Molecular Formula, Molecular Mass, Formula Unit Mass, Mole Concept, Atoms and Molecules Numericals, Laws of Chemical Combination, History of Atom, Law of Conservation of Mass, Law of Constant Proportions (Law of Definite Proportions), Dalton’s atomic theory, Atoms: Building Blocks of Matter, Symbols Used to Represent Atoms of Different Elements, Atomic Mass, Relative Atomic Mass (RAM), Molecules, Classification of Molecules, Difference Between Atoms and Molecules, Ions (Radicals) and Its Types, Chemical Formula or Molecular Formula, Molecular Mass, Formula Unit Mass, Mole Concept, Atoms and Molecules Numericals.

Using NCERT Science Class 9 solutions Atoms and Molecules exercise by students is an easy way to prepare for the exams, as they involve solutions arranged chapter-wise and also page-wise. The questions involved in NCERT Solutions are essential questions that can be asked in the final exam. Maximum CBSE Science Class 9 students prefer NCERT Textbook Solutions to score more in exams.

Get the free view of Chapter 3, Atoms and Molecules Science Class 9 additional questions for Mathematics Science Class 9 CBSE, and you can use Shaalaa.com to keep it handy for your exam preparation.

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