KVPY Sample Paper KVPY Stream-SX Model Paper-17

  • question_answer
    Given is the graph between \[{{(a-x)}^{-1}}\] and time.
    Hence, rate at the start of the reaction is:

    A) \[1.25\,mol\,\,{{L}^{-1}}{{\min }^{-1}}\]

    B) \[0.125\,\,mol\,\,{{L}^{-1}}{{\min }^{-1}}\]

    C) \[0.5\,\,mol\,\,{{L}^{-1}}{{\min }^{-1}}\]

    D) \[1.25\,\,mol\,\,{{\min }^{-1}}\]

    Correct Answer: B

    Solution :

    Since, the graph of t vs \[{{(a-x)}^{-1}}\] is a straight line, it must be a second order reaction.
    \[\therefore \]      \[K=\frac{1}{t}\,\,\left[ \frac{1}{(a-x)}-\frac{1}{a} \right]\]
    or         \[\frac{1}{a-x}=Kt+\frac{1}{a}\]
    On comparing, slope \[K=\tan \theta =0.5\,\,\text{mo}{{\text{l}}^{-1}}L{{\min }^{-1}}\]
                \[OA=\frac{1}{a}=2\,\,L\text{mo}{{\text{l}}^{-1}}\]
    or         \[a=\text{0}\text{.5}\,\,\text{mol}\,\,{{L}^{-1}}\]
                \[\text{Rate}=K\,{{(a)}^{2}}=0.5\times {{(0.5)}^{2}}\]
                \[=0.125\,\,mol\,\,{{L}^{-1}}{{\min }^{-1}}.\]


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