CET Karnataka Medical CET - Karnataka Medical Solved Paper-2001

  • question_answer
    The ionisation potential of hydrogen is 13.6 eV. Then the energy released when an electron jumps from n = 3 to n = 2 orbit, is:

    A)  2.89 eV       

    B)  1.89 eV

    C)  3.89 eV

    D)  4.89 eV

    Correct Answer: B

    Solution :

     The energy of electron in nth orbit of H-atom is \[{{E}_{n}}=\frac{Rhc}{{{n}^{2}}}\] Given ionisation potential = 13-6 eV so, ionisation energy Rhc = 13-6 eV So, \[{{E}_{n}}=-\frac{13.6}{{{n}^{2}}}eV\] In n = 2 orbit \[{{E}_{2}}=-\frac{13.6}{{{2}^{2}}}=-\frac{13.6}{4}=-3.4eV\] In n = 3 orbit \[{{E}_{3}}=-\frac{13.6}{{{3}^{2}}}\] \[=-\frac{13.6}{9}=1.51eV\] Energy released is \[\Delta E={{E}_{3}}-{{E}_{2}}\] \[=-1.51eV-(-3.4eV)\] \[=-1.5eV+3.4eV\] \[=1.89eV\]


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