NEET Sample Paper NEET Sample Test Paper-15

  • question_answer The energy of electron in the first energy level is \[-21.79\times {{10}^{-12}}\,\text{erg}\] per atom. The energy of electron in second energy level is

    A) \[-15.47\times {{10}^{-12}}\,\text{erg}\,\text{ato}{{\text{m}}^{-1}}\]

    B) \[-0.00547\times {{10}^{-12}}\,\text{erg}\,\text{ato}{{\text{m}}^{-1}}\]

    C) \[-4.557\times {{10}^{-12}}\,\text{erg}\,\text{ato}{{\text{m}}^{-1}}\]

    D) \[-5.447\times {{10}^{-12}}\text{erg}\,\text{ato}{{\text{m}}^{-1}}\]

    Correct Answer: D

    Solution :

    \[(E)=-\frac{{{Z}^{2}}}{{{n}^{2}}}\times 2.179\times {{10}^{-11}}\,\text{erg/atom}\text{.}\] For first energy level, \[n=1.\] \[{{E}_{1}}=-\frac{{{Z}^{2}}}{{{1}^{2}}}\times 2.179\times {{10}^{-11}}\,\text{erg/atom}\text{.}\] For secondary energy level, \[n=2.\]             \[{{E}_{2}}=-\frac{{{Z}^{2}}}{{{2}^{2}}}\times 2.179\times {{10}^{-11}}\,\text{erg/atom}\text{.}\]             On dividing \[{{E}_{2}}\]by \[{{E}_{1}},\]we obtain             \[\frac{{{E}_{2}}}{{{E}_{1}}}=\frac{-{{Z}^{2}}\times 2.179\times {{10}^{-11}}/{{2}^{2}}}{-{{Z}^{2}}\times 2.179\times {{10}^{-11}}/{{1}^{2}}}=\frac{1}{4}\] \[{{E}_{2}}=\frac{{{E}_{1}}}{4}=\frac{-21.79\times {{10}^{-12}}}{4}\text{erg/atom}\text{.}\] \[{{E}_{2}}=-5.447\times {{10}^{-12}}\,\text{erg/atom}\text{.}\] Hence, the correct option is [d].

adversite


You need to login to perform this action.
You will be redirected in 3 sec spinner

Free
Videos