CBSE  /  Class 9  /  Science  /  Structure of the Atom

  • 1. 
    Which of the following correctly represents the electronic distribution in the Mg atom?

  • 3, 8, 1
  • 2, 8, 2
  • 1, 8, 3
  • 8, 2, 2

  • 2. 
    Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in the discovery of

  • electron
  • proton
  • nucleus in the atom
  • atomic mass

  • 3. 
    The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

  • \(_{15}^{31}\)X
  • \(_{16}^{31}\)X
  • \(_{15}^{16}\)X
  • \(_{16}^{15}\)X

  • 4. 
    The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

  • 13
  • 10
  • 14
  • 16

  • 5. 
    The first model of an atom was given by

  • N. Bohr
  • E. Goldstein
  • Rutherford
  • J. J. Thomson

  • 6. 
    An atom with 3 protons and 4 neutrons will have a valency of

  • 3
  • 7
  • 1
  • 4

  • 7. 
    Which of the following statement is always correct?

  • An atom has equal number of electrons and protons.
  • An atom has equal number of electrons and neutrons.
  • An atom has equal number of protons and neutrons.
  • An atom has equal number of electrons, protons and neutrons.

  • 8. 
    Hydrogen exists in three isotopic forms, \(_{1}^{1}\)H, \(_{1}^{2}\)H, \(_{1}^{3}\)H known as protium, deuterium and tritium. Why are all the isotopes neutral in nature?

  • Since neutrons are neutral in nature hence isotopes are electrically neutral.
  • All the isotopes have one electron and one proton, hence they are neutral.
  • All the isotopes have one proton and one neutron, hence they are neutral.
  • Increasing number of protons in the isotopes make them neutral.

  • 9. 
    How many electrons are present in M-shell of an element with atomic number 20?

  • 5
  • 8
  • 12
  • 18

  • 10. 
    There are two atomic species X and Y, such that

  • X and Y are isobars.
  • X and Y have different chemical properties.
  • X and Y have different physical properties.
  • All of these.
Report Question
warning
Practice More On Structure of the Atom
Quiz 1 Quiz 2
access_time
  Time