Haryana PMT Haryana PMT Solved Paper-2008

  • question_answer
    A first order reaction complete ifs \[10%\] in 20 min then time required to complete-its \[19%\]is (log\[3=0.477\])

    A)  \[30\text{ }min\]

    B)  \[40min\]

    C)  \[38min\]    

    D)  \[45min\]

    Correct Answer: B

    Solution :

                    According to the 1st order of kinetics, \[t=\frac{2.303}{\lambda }\log \frac{a}{a-x}\] \[\frac{{{t}_{19%}}}{{{t}_{10%}}}=\frac{\log \frac{100}{100-19}}{\log \left( \frac{100}{100-10} \right)}\] \[=\frac{\log 100-\log 81}{\log \frac{10}{9}}\] \[\frac{{{t}_{19%}}}{20}=\frac{\log {{10}^{2}}-\log {{3}^{4}}}{\log 10-\log {{3}^{2}}}\] \[{{t}_{19%}}=\frac{(2-4\times 0.477)\times 20}{1-2\times 0.477}\] \[=40\min \]


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