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NEET AIPMT SOLVED PAPER SCREENING 2007

  • question_answer
                    Given that bond energies of H-H and CI-CI are \[430\,kJ\,mo{{l}^{-1}}\] and \[240\,kJ\,mo{{l}^{-1}}\] respectively and \[\Delta \]\[{{H}_{f}}\] for HCl is \[-90\,kJ\,mo{{l}^{-1}}\]. Bond enthalpy' of HCl is:                                                                                                       

    A)                 \[290\,kJ\,mo{{l}^{-1}}\]

    B)                 \[380\,kJ\,mo{{l}^{-1}}\]

    C)                         \[425\,kJ\,mo{{l}^{-1}}\]

    D)                 \[245\,kJ\,mo{{l}^{-1}}\]              

    Correct Answer: B

    Solution :

                    \[\Delta {{H}_{reaction}}={{\Delta }_{H-H}}+\Delta {{H}_{Cl-Cl}}-2\Delta {{H}_{HCl}}=-90\,kJ\]                 \[or\Delta {{H}_{H-Cl}}=\frac{430+240-(-90)}{2}\]                 \[=\frac{760}{2}=380\,kJ\,mo{{l}^{-1}}\]


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