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![NCERT solutions for Science [English] Class 9 chapter 3 - Atoms and Molecules - Shaalaa.com](/images/science-english-class-9_6:8626690beaa343fd99329119ec507003.jpg "NCERT solutions for Science [English] Class 9 chapter 3 - Atoms and Molecules")
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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 [English] Class 9.
NCERT solutions for Science [English] Class 9 3 Atoms and Molecules Intext question [Pages 27 - 35]
In a reaction, 5.3 g 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
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?
Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?
Which postulate of Dalton’s atomic theory can explain the law of definite proportions?
Define the atomic mass unit.
Why is it not possible to see an atom with naked eyes?
Write down the formulae of sodium oxide.
Write down the formula of aluminium chloride.
Write down the formulae of sodium sulphide.
Write down the formulae of magnesium hydroxide.
Write down the name of a compound represented by the following formula:
Al2(SO4)3
Write down the name of a compound represented by the following formula:
CaCl2
Write down the name of a compound represented by the following formula:
K2SO4
Write down the name of a compound represented by the following formula:
KNO3
Write down the name of a compound represented by the following formula:
CaCO3
What is meant by the term chemical formula?
How many atoms are present in a H2S molecule?
How many atoms are present in a `PO_4^(3-)` ion?
Calculate the molecular mass of H2.
Calculate the molecular mass of O2.
Calculate the molecular mass of Cl2.
Calculate the molecular mass of CO2.
Calculate the molecular mass of CH4.
Calculate the molecular mass of C2H6.
Calculate the molecular mass of C2H4.
Calculate the molecular mass of NH3.
Calculate the molecular mass of CH3OH.
Calculate the formula unit mass of ZnO given the atomic mass of:
- Zn = 65 u
- Na = 23 u
- K = 39 u
- C = 12 u
- O = 16 u
Calculate the formula unit mass of Na2O given the atomic mass of
- Zn = 65 u
- Na = 23 u
- K = 39 u
- C = 12 u
- O = 16 u
Calculate the formula unit mass of K2CO3 given the atomic mass of
- Zn = 65 u
- Na = 23 u
- K = 39 u
- C = 12 u
- O = 16 u
NCERT solutions for Science [English] Class 9 3 Atoms and Molecules Exercises [Page 36]
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.
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?
What are polyatomic ions? Give examples.
Write the chemical formula of the Magnesium chloride.
Write the chemical formula of the Calcium oxide.
Write the chemical formula of the Copper nitrate.
Write down the formula of aluminium chloride.
Write the chemical formula of the Calcium carbonate.
Give the name of the element present in the following compound:
Quick lime
Give the name of the element present in the following compound:
Hydrogen bromide
Give the name of the element present in the following compound:
Baking powder
Give the name of the element present in the following compound:
Potassium sulphate
Calculate the molar mass of the following substance:
Ethyne, C2H2
Calculate the molar mass of the following substance:
Sulphur molecule, S8
Calculate the molar mass of the following substance:
Phosphorus molecule, P4 (atomic mass of phosphorus = 31)
Calculate the molar mass of the following substance:
Hydrochloric acid, HCl
Calculate the molar mass of the following substance:
Nitric acid, HNO3
NCERT solutions for Science [English] Class 9 3 Atoms and Molecules Group Activity [Pages 36 - 37]
Play a game for writing formula.
Example 1: Make placards with symbols and valencies of the elements separately. Each student should hold two placards, one with the symbol in the right hand and the other with the valency in the left hand. Keeping the symbols in place, students should criss-cross their valencies to form the formula of a compound.
Play a game for writing formula.
Example 2: A low-cost model for writing formulae: Take empty blister packs of medicines. Cut them in groups according to the valency of the element, as shown in the figure. Now, you can make formulae by fixing one type of ion into other.
For example:
The formula for sodium sulphate:
2 sodium ions can be fixed on one sulphate ion.
Hence, the formula will be Na2SO4.
Do it yourself:
Now, write the formula of sodium phosphate.
Solutions for 3: Atoms and Molecules
NCERT solutions for Science [English] Class 9 chapter 3 - Atoms and Molecules
Shaalaa.com has the CBSE Mathematics Science [English] 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 [English] 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 [English] 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 [English] 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 [English] Class 9 students prefer NCERT Textbook Solutions to score more in exams.
Get the free view of Chapter 3, Atoms and Molecules Science [English] Class 9 additional questions for Mathematics Science [English] Class 9 CBSE, and you can use Shaalaa.com to keep it handy for your exam preparation.
