CH-3 Atoms and Molecules Class 9 The Class 9 Science Chapter 2 NCERT answers are all available here. This solution includes all of the material covered in Class 9’s Chapter 2: Is Matter around us Pure NCERT Solutions of Science, including questions, answers, illustrations, and step-by-step instructions. If you are a ninth-grade student studying science using the NCERT Textbook, you have probably encountered Chapter 1: Matter in Our Surroundings. You should be searching for the solutions to the questions after studying the lecture. All of the Class 9 Ch-2 Is Matter around us Pure NCERT Solutions are available right here. You should also refer to the Science class notes for Chapter 2 Is Matter around us Pure NCERT Solutions for a deeper understanding of this chapter.
Atoms and Molecules Class 9 NCERT Solutions Chapter 3 Intext Questions
Atoms and Molecules Class 9 NCERT Solutions
Question 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 of 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
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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?
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Question 3
Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?
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Question 4
Which postulate of Dalton’s atomic theory can explain the law of definite proportions?
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Atoms and Molecules Class 9 NCERT Solutions
Question 1
Define the atomic mass unit.
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Question 2
Why is it not possible to see an atom with naked eyes?
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Atoms and Molecules Class 9 NCERT Solutions
Question 1
Write down the formula of
- sodium oxide’
- aluminium chloride
- sodium sulphide
- magnesium hydroxide.
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Question 2
Write down the names of compounds represented by the following formulae:
- AI2(S04)3
- CaCI2
- K2S04
- KNO3
- CaCO3
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Question 3
What is meant by the term chemical formulae?
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Question 4
How many atoms are present in a
(i) H2S molecule and
(ii) P043- ion?
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Atoms and Molecules Class 9 NCERT Solutions
Question 1
Calculate the molecular masses of H2, O2 Cl2, CO2, CH4 C2H6, C2H4 NH3, CH3OH.
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Question 2
Calculate the formula unit masses of ZnO, Na2O, K2C03. Given atomic masses of Zn = 65 u, Na = 23 u, K = 39 u,C = 12 u and,0= 16 u.
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Atoms and Molecules Class 9 Exercise Questions (Textbook Chapter End Questions)
Atoms and Molecules Class 9 NCERT Solutions
Question 1
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.
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Question 2
When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.0 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.0 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combination will govern your answer?
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Question 3
What are polyatomic ions? Give examples.
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Question 4
Write the chemical formulae of the following:
(a) Magnesium chloride
(b) Calcium oxide
(c) Copper nitrate
(d) Aluminium chloride
(e) Calcium carbonate
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Question 5
Give the names of the elements present in the following compounds:
(a) Quicklime
(b) Hydrogen bromide
(c) Baking powder
(d) Potassium sulphate
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Question 6
Calculate the molar mass of the following substances:
(a) Ethyne, C2H2
(b) Sulphur molecule, S8
(c) Phosphorus molecule, P4 (atomic mass of phosphorus = 31)
(d) Hydrochloric acid, HCI
(e) Nitric acid, HN03
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