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EAMCET Medical EAMCET Medical Solved Paper-2008

  • question_answer
    The rate constant of a first order reaction is \[0.0693\,{{\min }^{-1}}.\] What is the time (in minutes) required for reducing an initial concentration of \[\text{20}\,\text{mol}\,{{\text{L}}^{-1}}\] to\[\text{2}\text{.5}\,\text{mol}\,{{\text{L}}^{-1}}\]?

    A)  40                                         

    B)  30

    C)  20                                         

    D)  10

    Correct Answer: B

    Solution :

                     Given,  \[k=0.0693{{\min }^{-1}}\] \[t=?\] \[a=20\,mol\,{{L}^{-1}}\] \[a-x=2.5\,mol\,{{L}^{-1}}\] \[k=\frac{2.303}{t}\log \frac{a}{a-x}\] \[t=\frac{2.303}{k}\log \frac{20}{2.5}\] \[t=\frac{2.303}{0.0693}\log 8\] \[=33.23\times 0.9030\,\min \] \[=30\min \]      


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