BCECE Engineering BCECE Engineering Solved Paper-2015

  • question_answer
    The energy required to excite the electron in  the atom from\[n=1\] to \[n=2,\], when the ionisation enthalpy of hydrogen atom is \[1.312\times {{10}^{6}}J\]/mol will be (in the unit of \[{{10}^{5}}\]).

    A) 8.53                       

    B) 7.51

    C) \[8.92\]                               

    D)  9.86

    Correct Answer: D

    Solution :

    \[{{E}_{2}}=\frac{-1.312\times {{10}^{6}}\times {{(1)}^{2}}}{{{(2)}^{2}}}\] \[\text{=-3}\text{.28 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{5}}}\text{J/mol}\] \[{{\text{E}}_{\text{1}}}\text{=-1}\text{.312 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{6}}}\text{J/mol}\] \[\therefore \]                  \[\Delta E={{E}_{2}}-{{E}_{1}}\] \[=-3.28\times {{10}^{6}}-(1.312\times {{10}^{6}})\] \[\text{= 9}\text{.84 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{5}}}\text{J/mol}\]


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