Telangana SCERT Class 9 Physical Science Chapter 9 What Is Inside The Atom Solution

Telangana SCERT Class 9 Physical Science Chapter 9 Solution – What Is Inside The Atom. Here in this post we provides Class 9 Physical Science What Is Inside The Atom Telangana State Board Solution. Telangana State Board English Class IX Medium Students can download this Solution to Solve out Improve Your Learning Questions and Answers.

Telangana State Board Class 9 Physical Science Chapter 9 What Is Inside The Atom Solution:



What Is Inside The Atom


Reflections on concepts

1) What are the three subatomic particles?

Ans: – The subatomic particles which are present in atom are electron, proton, neutron.

2) What were the three major observations Rutherford made in the gold foil experiment?

Ans: – The three main observations that Rutherford made is-

  • Atom’s nucleus is not empty as some of gold particles get reflected.
  • Maximum passes through the gold foil.
  • Some percentage get reflected.

3) Give the main postulates of Bohr’s model of an atom.

Ans: – The electron is removing around a nucleus. And there is different energy level in an atomic model and for going up higher energy level energy is required and for going down energy release.

4) State the valences of magnesium and sodium.

Ans: – The valances of magnesium are 2 and sodium valances is 1.


Application of concepts

1) Compare the sub-atomic particles electron, proton and neutron.

Ans: – There are three sub atomic particles in an atom these are electron, proton and neutron. This electron is negatively charged particles which takes part in reaction. The proton is positively charged particles and neutron is neutral in nature.

2) What are the limitations of J.J. Thomson’s model of the atom?

Ans: – The JJ Thomson models have some limitations as this model doesn’t gave the prove of explanation of scattering of alpha particles in Rutherford gold foil scattering and this model also have no prove its only has imagination model in Thomson statement.

3) Define valency by taking examples of nitrogen and boron.

Ans: – The valency of an atom is known as the no of electron in the outermost shell which takes part in the formation of another compound by donation or receiving. The valancy of nitrogen and boron is 3.

4) What is the main difference among the isotopes of the same element? (AS1)

Ans: – The mail difference among the isotopes of the same elements is this all have different mass number and also have different neutron number.

5) Fill in the missing information in the following table.

Ans: –

Higher Order Thinking Questions

1) Cl – has completely filled K, L & M shells. Explain it based on Bhor-Bury theory. (AS1)

Ans: – In Cl element has only 17 electrons but Cl- has 18 electron which gave the configuration of full of the outermost shell. The K shell has 2 electron, L shell has 8 electron and M shell has 8 electrons.

2) Explain the efforts made by scientists to explain the structure of atom by developing various atomic models? (AS6)

Ans: –  The various atomic model which have discovered by various scientific research of the scientist gave the clear idea about this. The first atomic model is Dalton atomic model then came different atomic model like Rutherford atomic model, JJ Thomson model. This developing of different atomic models gave the clear idea about the atomic structure.



1.) Electron was invented by

a) Thomson b) Chadwick c) Goldstein d) Stoney.

Ans: – Option (a).

2.) Proton was invented by

b) Thomson b) Chadwick c) Goldstein d) Stoney.

Ans: – option (c).

3.) Neutron was invented by

a) Thomson b) Chadwick c) Goldstein d) Stoney.

Ans: – Option (b).

4.) α – particles are made up of the following primary particles

a) 2 protons and 2 neutrons b) 2 Protons and 2 Electrons

c) 2 Neutrons and 2 Positrons d) 2 Protons and 2 Neutrinos.

Ans: –  option (c).

5.) Which model of atom is known as Planetary model

a) Thomson’s model b) Rutherford’s model

c) Bohr’s model d) Modern atomic model.

Ans: – option (b).

6.) Valency of Aluminium is

a) 1 b) 2 c) 3 d) 4.

Ans: – option (c).

7.) The gas which is stable without octetconfiguration is

a) Neon b) Argon c) Radon d) Helium.

Ans: – Option (d).

8.) The sum of the number of protons and neutrons in an atom is knownas its

a) Mass number b) Atomic number c) Valency d) Ion number.

Ans: – option (a).

9.) Deuterium and Tritium are the Isotopes of —

a) Nitrogen b) Oxygen c) Hydrogen d) Helium.

Ans: – Option (c).

10.) The electronic configuration of Sodium is

a) 2,8 b) 8,2,1 c) 2,1,8 d) 2,8,1.

Ans: – Option (b).

Updated: January 27, 2022 — 10:36 am

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  1. Good idea for the students to improve their knowledge by knowing these answers in short way. Thank you for your answers which are supporting the children alot..

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