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DUMET Medical DUMET Medical Solved Paper-2008

  • question_answer
    The specific rotation of a pure enantiomer is\[+{{10}^{o}}\]. The observed rotation, if it is isolated from a reaction with 30% racemisation and 70% retention, is

    A)  \[+{{10}^{o}}\]         

    B)  \[+{{7}^{o}}\]

    C)  \[+{{14}^{o}}\]          

    D)  \[-{{7}^{o}}\]

    Correct Answer: B

    Solution :

    As there is 30% racemisation, the given mixture contains \[=\left( 70+\frac{30}{2} \right)%\] d-isomer and \[\left( \frac{30}{2} \right)%\] \[l-\]isomer. \[\therefore \] Specific rotation of mixture \[=\frac{85\times {{10}^{o}}}{100}+\frac{15(-{{10}^{o}})}{100}={{7}^{o}}\].


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