JEE Main & Advanced JEE Main Paper (Held On 10 April 2015)

  • question_answer
    The heat of atomization of methane and ethane are 360 kJ/mol and 620 kJ/mol, respectively. The longest wavelength of light capable of breaking the C - C bond is (Avogadro number \[=6.02\times {{10}^{23}},h=6.62\times {{10}^{-34}}Js\]) JEE Main Online Paper (Held On 10 April 2015)

    A) \[1.49\times {{10}^{3}}nm\]                       

    B) \[2.48\times {{10}^{4}}nm\]

    C) \[2.48\times {{10}^{3}}nm\]                       

    D) \[1.49\times {{10}^{4}}nm\]

    Correct Answer: A

    Solution :

                     In \[C{{H}_{4}}4\times B{{E}_{(C-H)}}=360KJ/mol\] \[\therefore \]\[B{{E}_{(C-H)}}=90KJ/mol\] In\[{{C}_{2}}{{H}_{6}}B{{E}_{(C-C)}}+6\times B{{E}_{(C-H)}}=620KJ/mol\] \[\therefore \]\[B{{E}_{(C-C)}}=80KJ/mol\] \[\therefore \]\[B{{E}_{(C-C)}}=\frac{80\times {{10}^{3}}}{6.023\times {{10}^{23}}}\text{J/molecule}\] Now, \[E=\frac{hc}{\lambda }\] \[\therefore \]\[\lambda =\frac{6.626\times {{10}^{-34}}\times 3\times {{10}^{8}}\times 6.023\times {{10}^{23}}}{80\times {{10}^{3}}}\] \[\therefore \]\[\lambda =1.49\times {{10}^{3}}nm\]


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