SSC Worksheet for chapter-1 Inside the Atom class 9

Worksheet For class 9

Fill in the Blanks

  1. The name atom was first proposed by __________.
  2. Presence of charge neutrality with in an atom is accredited to ________.
  3. In well know gold foil experiment source of alpha particles were
    1. nuclear fusion of
    2. radioactive decay
    3. chemical reaction of atom
    4. none
  4. Thickness of gold foil in Rutherford experiment was __________cm.
  5. Electrons revolve around nucleus in a fixed path known as __________.
  6. According to Bohr’s model, electron could jump between fixed orbits but not freely. (True/ False)
  7. Discovery of neutron was done by__________ is year___________.
  8. Atomic orbits are also known as ____________.
  9. Maximum number of electrons in 9th shell is given by __________.
  10. Energy of electrons in subsequent higher orbit keeps on _________.
  11. Calcium 2+ion(Ca2+ ) has 18 electrons in its atom. Its atomic number is _________.
  12. 1 amu is equal to ____________ kg.
  13. Number of proton and neutron in a carbon atom is 6 & 8 respectively and that of a nitrogen atom is of 7 respectively. Their mass number is ________ and _______. There for they are __________.
  14. Electronic Configuration of oxygen is _________.
  15. Nucleons are present inside __________.


  1. Explain drawbacks of Thomson’s theory of atom.
  2. What are Rutherford’s Gold Foil experimental findings and his propositions based on these facts.
  3. How did Bohr’s atomic model account for drawback of Rutherford model?
  4. What are subatomic particles, name them?
  5. What is electronic configuration?

For other SSC Worksheet for class 9 Science check out main page of Physics Wallah.


  1. Democritus
  2. J Thomson
  3. b
  4. 0.00004
  5. Orbit
  6. True
  7. James Chadwick , 1932
  8. shells
  9. 162
  10. Increasing
  11. 20
  12. 1 .67377 × 10-27
  13. 14, 14, Isobars
  14. 2, 6
  15. Nucleus
  16. Draw back of Thompsons theory
    1. Conduction of electricity was not well explained based on electron election
    2. Nothing regarding nucleus was explained.
  17. fixing of Gold foil experiment:
    1. Most of particles passed straight
    2. Some deviated at small angles
    3. A very few bounced bank towards the source
    1. (i) Atom has a tiny, dense, positively changed core could a nucleus in which mass of an atom is concentrated.
    2. (ii) The Light relatively changed electrons revolve around the nucleus is paths called orbits like solar system
  18. Revision is Rutherford’s model by Nails Bohr
    1. (i) The electrons were confincal is to clearly defined orbit
    2. (ii) They could not jump forcely in ward or outward
    3. (iii) For any jump is orbit: is has is absorb or emit energy
  19. Electron, proton, Neutron, Portion, Boson etc.
  20. Electronic configuration: The arrangement of electrons is different credits & orbits to explain & understand the chemical behavior of atoms known a electronic configuration.

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