NEET Sample Paper NEET Sample Test Paper-85

  • question_answer
    An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be

    A) \[\frac{24hR}{25m}\]

    B)        \[\frac{25hR}{24m}\]

    C) \[\frac{25m}{24hR}\]    

    D)        \[\frac{24m}{25hR}\]

    Correct Answer: A

    Solution :

    [a] For emission, the wave number of the radiation is given as \[\frac{1}{\lambda }=R{{z}^{2}}\left( \frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}} \right)\] R= Rydberg constant, z = atomic number \[=R\left( \frac{1}{{{1}^{2}}}-\frac{1}{{{5}^{2}}} \right)=R\left( 1-\frac{1}{25} \right)\] \[\Rightarrow \]   \[\frac{1}{\lambda }=R\frac{24}{25}\] linear momentum \[P=\frac{h}{\lambda }=h\times R\times \frac{24}{25}\](de-Broghe hypofliesis) \[\Rightarrow \]   \[mv=\frac{24hR}{25}\Rightarrow \,\,v=\frac{24hR}{25m}\]        


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