JEE Main & Advanced Sample Paper JEE Main Sample Paper-46

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

    A)  \[1.25\,\,mo{{l}^{-1}}{{\min }^{-1}}\]

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

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

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

    Correct Answer: C

    Solution :

     Since, the graph of \[t\,vs\,\,{{(a-x)}^{-1}}\] or \[\frac{1}{a-x}\] is a straight line, it must be a second order reaction and for a second order reaction, \[K=\frac{1}{t}\,\left[ \frac{1}{(a-x)}-\frac{1}{a} \right]\] \[\frac{1}{a-x}={{K}_{t}}+\frac{1}{a}\] On comparing, slope \[=K=\tan \,\theta =0.5\,mo{{l}^{-1}}\,{{\sin }^{-1}}\] \[OA=\frac{1}{a}=2L\,mol\] 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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