BCECE Engineering BCECE Engineering Solved Paper-2004

  • question_answer
    If \[n=3,\,l=0\]and \[m=0,\]then atomic number   is:

    A) 12 or 13               

    B)        13 or 14

    C) 10 or 11               

    D)        11 or 12

    Correct Answer: D

    Solution :

    Key Idea: The values of quantum number will give idea about the last subshell of element. From that value we can find the atomic number of element, \[n=3\]means \[3rd\] shell \[\left. \begin{matrix}    l=0  \\    m=0  \\ \end{matrix} \right\}\text{means}\,\text{sub}\,\text{shell}\] It means it is 3s subshell which can have 1 or 2 electrons. \[\therefore \] Configuration of element is \[1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{1-2}}\] \[\therefore \] Atomic no. is 11 or 12


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