KVPY Sample Paper KVPY Stream-SX Model Paper-1

  • 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 :

    [B]
    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
    \[K=\tan \theta =0.5\,\,mo{{l}^{-1}}L\,{{\min }^{-1}}\]
    \[OA=\frac{1}{a}=2\,\,L\,mo{{l}^{-1}}\]
    Or \[a=0.5\,\,mol\,{{L}^{-1}}\]
    Rate \[=K{{(a)}^{2}}=0.5\times {{(0.5)}^{2}}\]
    \[=0.125\,mol\,{{L}^{-1}}{{\min }^{-1}}\]


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