NEET Chemistry Structure of Atom / परमाणु संरचना NEET PYQ-Structure of Atom

  • question_answer
    The frequency of radiation emitted when the electron falls from \[n=4\] to \[n=1\] in a hydrogen atom will be (Given ionisation energy of \[H=2.18\,\,{{10}^{-18}}J\,ato{{m}^{-1}}\] and \[h=6.625\times {{10}^{-34}}Js):\]                                      [AIPMT (S) 2004]

    A)  \[1.54\times l{{0}^{15}}\text{ }{{s}^{-1}}\]

    B)       \[1.03\times {{10}^{15}}\,\,{{s}^{-1}}\]

    C)  \[3.08\times {{10}^{15}}\text{ }{{s}^{-1}}\]

    D)       \[2.00\times {{10}^{15}}\text{ }{{s}^{-1}}\]

    Correct Answer: C

    Solution :

    Ionization energy of \[H=2.18\times {{10}^{-18}}J\,ato{{m}^{-1}}\]
    \[\therefore \]      \[{{E}_{1}}\] (Energy of 1st orbit of H-atom)
    \[=-2.18\times l{{0}^{-18}}\text{ }J-ato{{n}^{-1}}\]
    \[\therefore \]      \[{{E}_{n}}=\frac{-2.18\times {{10}^{18}}}{{{n}^{2}}}J-ato{{m}^{-1}}\]
    \[Z=1\] for \[H-atom\]
    \[\Delta E={{E}_{4}}-{{E}_{1}}\]
    \[=\frac{-2.18\times {{10}^{-18}}}{{{4}^{2}}}-\frac{-2.18\times {{10}^{-18}}}{{}}\]
    \[=-2.18\times {{10}^{-18}}\times \left[ \frac{1}{{{4}^{2}}}-\frac{1}{{{1}^{2}}} \right]\]
                \[\Delta E=hv=-2.18\times {{10}^{-18}}\times -\frac{15}{16}\]
    \[=+\,2.0437\times {{10}^{-18}}J\,ato{{m}^{-1}}\]
    \[\therefore \]      \[V=\frac{\Delta E}{h}=\frac{2.0437\times {{10}^{-18}}J\,ato{{m}^{-1}}}{6.625\times {{10}^{-34}}\,J\,\,s}\]
    \[=3.084\times {{10}^{15}}\text{ }{{s}^{-1}}\text{ }ato{{m}^{-1}}\]


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