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![NCERT solutions for Science [English] Class 9 chapter 4 - Structure of the Atom - Shaalaa.com](/images/science-english-class-9_6:8626690beaa343fd99329119ec507003.jpg "NCERT solutions for Science [English] Class 9 chapter 4 - Structure of the Atom")
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Solutions for Chapter 4: Structure of the Atom
Below listed, you can find solutions for Chapter 4 of CBSE NCERT for Science [English] Class 9.
NCERT solutions for Science [English] Class 9 4 Structure of the Atom Intext question [Pages 39 - 45]
What are canal rays?
If an atom contains one electron and one proton, will it carry any charge or not?
On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Draw a sketch of Bohr’s model of an atom with three shells.
What do you think would be the observation if the α-particle scattering experiment is carried out using a foil of a metal other than gold?
Name the three sub-atomic particles of an atom.
Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?
Write the distribution of electrons in carbon and sodium atoms?
If K and L shells of an atom are full, then what would be the total number of electrons in the atom?
How will you find the valency of chlorine, sulphur and magnesium?
If number of electrons in an atom is 8 and number of protons is also 8, then
- What is the atomic number of the atom? and
- What is the charge on the atom?
With the help of given Table, find out the mass number of oxygen.
| Composition of Atoms of the First Eighteen Elements with Electron Distribution in Various Shells | ||||||||||
| Name of Element | Symbol | Atomic Number | Number of protons | Number of Neutrons | Number of Electrons | Distribution of Electrons | Valency | |||
| K | L | M | N | |||||||
| Hydrogen | H | 1 | 1 | - | 1 | 1 | - | - | - | 1 |
| Helium | He | 2 | 2 | 2 | 2 | 2 | - | - | - | 0 |
| Lithium | Li | 3 | 3 | 4 | 3 | 2 | 1 | - | - | 1 |
| Beryllium | Be | 4 | 4 | 5 | 4 | 2 | 2 | - | - | 2 |
| Boron | B | 5 | 5 | 6 | 5 | 2 | 3 | - | - | 3 |
| Carbon | C | 6 | 6 | 6 | 6 | 2 | 4 | - | - | 4 |
| Nitrogen | N | 7 | 7 | 7 | 7 | 2 | 5 | - | - | 3 |
| Oxygen | O | 8 | 8 | 8 | 8 | 2 | 6 | - | - | 2 |
| Fluorine | F | 9 | 9 | 10 | 9 | 2 | 7 | - | - | 1 |
| Neon | Ne | 10 | 10 | 10 | 10 | 2 | 8 | - | - | 0 |
| Sodium | Na | 11 | 11 | 12 | 11 | 2 | 8 | 1 | - | 1 |
| Magnesium | Mg | 12 | 12 | 12 | 12 | 2 | 8 | 2 | - | 2 |
| Aluminium | Al | 13 | 13 | 14 | 13 | 2 | 8 | 3 | - | 3 |
| Silicon | Si | 14 | 14 | 14 | 14 | 2 | 8 | 4 | - | 4 |
| Phosphorus | P | 15 | 15 | 16 | 15 | 2 | 8 | 5 | - | 3.5 |
| Sulphur | S | 16 | 16 | 16 | 16 | 2 | 8 | 6 | - | 2 |
| Chlorine | Cl | 17 | 17 | 18 | 17 | 2 | 8 | 7 | - | 1 |
| Argon | Ar | 18 | 18 | 22 | 18 | 2 | 8 | 8 | 0 | |
For the symbol H, D and T tabulate three sub-atomic particles found in each of them.
Write the electronic configuration of any one pair of isotopes and isobars.
NCERT solutions for Science [English] Class 9 4 Structure of the Atom Exercises [Pages 46 - 48]
Compare the properties of electrons, protons and neutrons.
What are the limitations of J.J. Thomson’s model of the atom?
What are the limitations of Rutherford’s model of the atom?
Describe Bohr’s model of the atom.
Compare all the proposed models of an atom given in this chapter.
Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.
Define valency by taking examples of silicon and oxygen.
Explain the Atomic number with example.
Explain the Mass number with example.
Explain the Isotopes with example.
Explain the Isobars with example.
Give any two uses of isotopes.
Na+ has completely filled K and L shells. Explain.
If bromine atom is available in the form of, say, two isotopes `""_35^79Br (49.7%)" and """_35^81Br (50.3%)`, calculate the average atomic mass of bromine atom.
The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes `""_8^16X" and """_8^18X` in the sample?
If Z = 3, what would be the valency of the element? Also, name the element.
The composition of the nuclei of two atomic species X and Y are given as under
| X | Y | |
| Protons | 6 | 6 |
| Neutrons | 6 | 8 |
Give the mass numbers of X and Y. What is the relation between the two species?
For the following statements, write True and False.
J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
True
False
A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.
True
False
The mass of an electron is about `1/2000` times that of proton.
True
False
An isotope of iodine is used for making tincture iodine, which is used as a medicine.
True
False
Choose the correct choice in questions 15, 16 and 17.
Rutherford’s alpha-particle scattering experiment was responsible for the discovery of ______.
Atomic nucleus
Electron
Proton
Neutron
Isotopes of an element have ______.
The same physical properties.
Different chemical properties.
Different numbers of neutrons.
Different atomic numbers.
Number of valence electrons in Cl− ion are ______.
16
8
17
18
Which one of the following is a correct electronic configuration of sodium?
2, 8
8, 2, 1
2, 1, 8
2, 8, 1
Complete the following table.
| Atomic number | Mass number | Number of Neutrons | Number of protons | Number of electrons | Name of the Atomic species |
| 9 | - | 10 | - | - | - |
| 16 | 32 | - | - | - | Sulphur |
| - | 24 | - | 12 | - | - |
| - | 2 | - | 1 | - | - |
| - | 1 | 0 | 1 | 0 | - |
Solutions for 4: Structure of the Atom
NCERT solutions for Science [English] Class 9 chapter 4 - Structure of the Atom
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 4 (Structure of the Atom) 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 4 Structure of the Atom are Existence of Charged Particles in Matter, Atoms: Building Blocks of Matter, Discovery of Charged Particles in Matter, Protons (p), Electrons (e), Neutrons (n), J. J. Thomson’s Atomic Model, Lord Rutherford’s Atomic model, Neils Bohr’s Model of an Atom, Electronic Configuration of Atom, Atomic Number (Z), Mass Number (A), and Number of Neutrons (n), Isotopes, Isobars, Atoms and Molecules Numericals, Valency, Uses of Radioactive Isotopes, Advantage and Limitations of Thomson’s Atomic Model, Limitations of Rutherford’s Atomic Model, Different Ways to Determine Valency, Atomic Mass, Existence of Charged Particles in Matter, Atoms: Building Blocks of Matter, Discovery of Charged Particles in Matter, Protons (p), Electrons (e), Neutrons (n), J. J. Thomson’s Atomic Model, Lord Rutherford’s Atomic model, Neils Bohr’s Model of an Atom, Electronic Configuration of Atom, Atomic Number (Z), Mass Number (A), and Number of Neutrons (n), Isotopes, Isobars, Atoms and Molecules Numericals, Valency, Uses of Radioactive Isotopes, Advantage and Limitations of Thomson’s Atomic Model, Limitations of Rutherford’s Atomic Model, Different Ways to Determine Valency, Atomic Mass.
Using NCERT Science [English] Class 9 solutions Structure of the Atom 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.
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