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

  • question_answer
      In the following table, the mass number and the atomic number of certain elements are given.                       
    Elements A B C D E
    Mass number 1 7 14 40 40
    Atomic number 1 3 7 18 20
    (a) How many neutrons are present in B and D? (b) What would be the valency of element 'B' listed in the above table?

    Answer:

              (a) Number of neutrons in 5 = 7 ? 3 = 4 Numbers of neutrons in D = 40 -18 = 22.    (b) Electronic configuration of the element B  is 2, 1. Therefore, its valency is 1.


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