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JEE Main & Advanced Sample Paper JEE Main Sample Paper-47

  • question_answer
    Acetic acid dimerises in benzene due to hydrogen bond. 1 mol acetic acid is added to 250 g benzene. \[{{K}_{b}}\]of benzene is 2 \[2\,K\,kg\cdot mo{{l}^{-1}}\]. The boiling point has increased by 6.4K. percentage dimidiation of by of acetic acid is

    A)  20                              

    B)  30               

    C)  40                              

    D)  50

    Correct Answer: C

    Solution :

     \[\Delta {{T}_{b}}=i{{K}_{b}}\cdot \,m\] \[m=\frac{1\times 1000}{250}=4\,m\]         \[\therefore \] \[6.4=I\times 2\times 4\] or \[i=0.8\] For dimeristion \[i=1-\frac{\alpha }{2}\]\[\Rightarrow \]        \[0.8-1=\frac{-\alpha }{2}\] or         \[\alpha =0.4\,\,\Rightarrow \,\,40%\]


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