most important questions, class 9, chapter 3

  1. State the location of electrons and protons in an atom.
  2. Which of the two atomic numbers or atomic mass determines the chemical properties of an element?
  3. What is an orbit, shell or energy level?
  4. What is a valence shell?
  5. What are valence electrons?
  6. Write the electronic configuration of an element X whose atomic number is 12.
  7. What is the maximum number of electrons an M shell of the atom can accommodate?
  8. If both K and L shells of an atom are full,what is the total number of electrons contained in them?
  9. Write the electronic configuration of the element with atomic number 20.Indicate the valency of the element.
  10. How many electrons will be present in K,L and M energy shells of atoms of elements with atomic numbers (i) 11 and (ii) 18?
  11. Who discovered anode (canal) rays?
  12. Which the lighter. A proton or an electron?
  13. Name the gas which gives the lightest positively charged particle.
  14. Name the fruit which resembles Thomson model of atom.
  15. Which metal foil was used by Rutherford in his experiment for the discovery of nucleus?
  16. Electron in an atom jumps from K to L shell. Will the energy be absorbed or evolved?