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9th Class Science Structure of the Atom Question Bank Structure of Atom

  • question_answer
    A brief information about two atoms
    X and Y is given: X: Atomic number = 7, Mass number = 14
    Y: Atomic number = 7, Mass number = 15
    Which of the following is correct about these two atoms?

    A) Electronic configuration of X is 2, 8, 4 while that of Y is 2, 8, 5.

    B) Both X and Y contain 7 neutrons.

    C) X has 2 electron shells while Y has 3 electron shells.

    D) Both X and Y have 5 valence electrons.

    Correct Answer: D

    Solution :

    X and Y are isotopes having electronic configuration as 2, 5. Hence, both have five valence electrons.


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