Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2009

  • question_answer
    In first order reaction, the concentration of reactant decreases from \[800\text{ }mol\text{ }c{{m}^{-3}}\]to \[50\text{ }mol\text{ }c{{m}^{-3}}\]in \[2\times {{10}^{4}}s.\]. The rate constant is

    A)  \[2\times {{10}^{4}}{{s}^{-1}}\]

    B)  \[3.45\times {{10}^{-5}}{{s}^{-1}}\]

    C)  \[1.386\times {{10}^{-4}}{{s}^{-1}}\]

    D)  \[2\times {{10}^{-4}}{{s}^{-1}}\]

    Correct Answer: C

    Solution :

    For first order reaction, Rate constant, \[k=\frac{2.303}{t}\log \frac{a}{a-x}\] \[\Rightarrow \]               \[k=\frac{2.303}{2\times {{10}^{4}}}\log \frac{800}{50}\]                 \[=1.386\times {{10}^{-4}}{{s}^{-1}}\]


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