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NEET Sample Paper NEET Sample Test Paper-27

  • question_answer
    The wavelength of \[{{K}_{d}}\] line from element of atomic number 51 is\[\lambda \]. From another element the wavelength of \[{{K}_{d}}\] line is\[4\lambda \]. What is the atomic number of the second element?

    A) 25

    B) 26

    C) 100

    D) 99

    Correct Answer: B

    Solution :

    From the relation, \[\lambda \propto \frac{1}{{{(Z-1)}^{2}}}\] First case Given that,        \[Z=51\] i.e.       \[\lambda \propto \frac{1}{{{(51-1)}^{2}}}\propto \frac{1}{{{(50)}^{2}}}\] Second case   \[4\lambda \propto \frac{1}{{{(Z-1)}^{2}}}\] \[\Rightarrow \]            \[\frac{4}{{{(50)}^{2}}}=\frac{1}{{{(Z-1)}^{2}}}\]  \[\left( \because \,\,\,\,\lambda \propto \frac{1}{{{(50)}^{2}}} \right)\] \[\Rightarrow \]            \[Z=26\]


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