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9th Class Science Structure of the Atom Question Bank Atomic Structure Conceptive Objective Problems

  • question_answer
    The total number of protons present in all the elements up to Zn in the periodic table is

    A)  300                       

    B)  350  

    C)  465       

    D)  450

    Correct Answer: C

    Solution :

        The atomic number of zinc is 30.                                                                                              \[\Rightarrow\] Total no. of protons                                                                                  \[=1+2+3+.................+30\] . Sum of first ?n? natural numbers                                                                                        \[=\frac{n(n+1)}{2}\]                                                                                              \[\Rightarrow\] Total no. of protons                                                                 \[=\frac{30\times 31}{2}=15\times 31=465\]                


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