NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules download in PDF file updated for academic session 2023-24 in Hindi and English Medium based on rationalised NCERT Books published for 2023-24 examination.
NCERT Solutions for Class 9 Science Chapter 3
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UP Board High School students can download UP Board Solutions in Hindi Medium here. 9th Science chapter 3 Page 32, Page 33, Page 35, Page 39, Page 40, Page 42 and Exercises answers with explanation in English Medium or Page 36 ke Uttar, Page 40 ke Uttar, Page 44 ke Uttar, Page 46 ke Uttar, Page 48 ke Uttar and Abhyaas ke Uttar in Hindi Medium free to study online or in PDF form to use offline.
Download NCERT Solutions 2023-24 and NCERT Solutions Apps for other subjects are also in same format. All the contents are updated for new session based on latest CBSE Syllabus 2023-24.
|Contents:||NCERT Solutions and Important Questions|
|Chapter 3:||Atoms and Molecules|
|Content Type:||PDF, Text and Videos|
|Medium:||English and Hindi Medium|
9th Science Chapter 3 Answers in English & Hindi Medium
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We have updated all the contents for new session 2023-24 for CBSE, UP Board, MP Board, etc., who are following NCERT Books 2023-24 and latest CBSE Syllabus 2023-24.
Extra Questions on 9th Science Chapter 3
Why is a cation so named?
When electric current is passed through the solution of a salt like sodium chloride (NaCl), the positive ion (Na+) migrates towards cathode (negative electrode). It is therefore, called cation. Remember this:
(i) Positive ion migrating towards cathode on passing electric current is known as cation.
(ii) Negative ion migrating towards anode on passing electric current is known as anion.
The atomic mass of an element is in fraction. What does it means?
If the atomic mass of an element is in fraction, this means that it is existed in the form of isotopes. The atomic mass is the average atomic mass and it is generally fractional.
Why are chemical reaction according to law of conservation of mass?
In all chemical reactions, there is only exchange of reactants taking place when products are formed. Since there is no loss or gain of mass, the chemical reactions are according to law of conservation of mass.
Give one limitation of law of constant composition.
The law of constant composition does not hold when different isotopes of an element take part in the formation of a particular compound. For example,
In carbon dioxide (CO2)
By using C-12 isotopes, the ratio of C : O is 12 : 32.
By using C-14 isotopes, the ratio of C : O is 14 : 32.
This means that the two ratios are not the same.
Out of atoms and molecules which can exist independently?
Molecules can exist independently. However, the atoms of noble gases (He, Ne, Ar, Kr, Xe) can also exist independently.
Questions for Practice on 9th Science Chapter 3
In what respect does Dalton’s Atomic theory hold good even today?
atom has been found to be made up of sub-atomic particles like electrons, protons and neutrons. But it is still the smallest particle of matter which can take can take part in chemical combination.
Why is it necessary to balance a chemical equation?
A chemical equation has to be balanced in order to satisfy the law of conservation of mass. According to the law, there is no change in mass when the reaction changes into the production. Therefore, the chemical equation has to be balanced.
What is basic different between atoms and molecules?
Atoms except those of noble or inert gas elements cannot exist of their own. However, all molecules can have independent existence.
Important Questions on 9th Science Chapter 3
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?
Carbon + Oxygen → Carbon dioxide 3g of carbon reacts with 8 g of oxygen to produce 11g of carbon dioxide. If 3g of carbon is burnt in 50g of oxygen, then 3g of carbon will react with 8 g of oxygen. The remaining 42 g of oxygen will be left un-reactive. In this case also, only 11g of carbon dioxide will be formed. The above answer is governed by the law of constant proportions.
What is the mass of 4 mole of aluminium atoms (Atomic mass of aluminium = 27)?
The mass of 4 moles of aluminium atoms is (4 × 27)g = 108g
Convert into mole: 12g of oxygen gas.
32 g of oxygen gas = 1 mole Then, 12g of oxygen gas = 12/32 mole = 0.375 mole
What is the mass of 0.2 mole of oxygen atoms?
Mass of one mole of oxygen atoms = 16g Then, mass of 0.2 mole of oxygen atoms = 0.2 × 16g = 3.2g