NEET Sample Paper NEET Sample Test Paper-14

  • question_answer Calculate the wavelength of light required to break the bond between two chlorine atoms in a chlorine molecule. The \[CI-CI\]bond energy is\[243\,kJ\,mo{{l}^{-1}}\]\[(h=6.6\times {{10}^{-34}}J\,s;\]\[c=3\times {{10}^{8}}\,m/s;)\]Avogadro's number \[=6.02\times {{10}^{23}}\text{mo}{{\text{l}}^{-1}}\]

    A) \[8.18\times {{10}^{-31}}m\]         

    B) \[6.26\times {{10}^{-21}}m\]

    C) \[4.91\times {{10}^{-7}}m\]           

    D)  \[4.1\times {{10}^{-6}}m\]  

    Correct Answer: C

    Solution :

    Energy required to break one Cl-Cl bond \[=\frac{\text{Bond}\,\text{enegy}\,\text{permole}}{\text{Avogadro }\!\!'\!\!\text{ s}\,\text{number}}\] \[=\frac{243\times {{10}^{3}}}{6.02\times {{10}^{23}}}J\] Let the wavelength of the photon to cause rupture of one Cl-Cl bond be\[\lambda \], \[\lambda =\frac{hc}{E}=\frac{6.6\times {{10}^{8}}\times 6.02\times {{10}^{23}}}{243\times {{10}^{3}}}\] \[=\frac{119.196}{243}\times {{10}^{-34}}\times {{10}^{31}}\times {{10}^{-3}}\] Therefore, \[\lambda =4.91\times {{10}^{-7}}\,m.\] Hence, the correct option is [c].

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