NCERT Class-9 Science Solutions: Chapter 4-Structure of the Atom Part 4 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 18:

Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order

  1. Rutherford՚s atomic model
  2. Thomson՚s atomic model
  3. Bohr՚s atomic model
  4. (i) , (ii) and (iii)
  5. (ii) , (iii) and (i)
  6. (ii) , (i) and (iii)
  7. (iii) , (ii) and (i)

Answer: C

Short Answer Questions

Question 19:

Is it possible for the atom of an element to have one electron, one proton and no neutron? If so, name the element.


Yes, it is true for hydrogen atom which is represented as

Question 20:

Write any two observations which support the fact that atoms are divisible.


Discovery of electrons and protons

Discovery of Protons
Discovery of Electrons

Question 21:

Will have different valency? Justify your answer.


No, are isotopes of an element.

Question 22:

Why did Rutherford select a gold foil in his scattering experiment?


Gold has high malleability

Question 23:

Find out the valency of the atoms represented by the Fig, (a) and (b) .

Result for Valency of the Atoms


  1. 0
  2. 1

Question 24:

One electron is present in the outer most shell of the atom of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outer most shell?


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