JEE Main & Advanced Sample Paper JEE Main - Mock Test - 22

  • question_answer
    Following are two first order reactions with their half times given at\[25{}^\circ C\].
    \[A\xrightarrow{{{t}_{1/2}}=30\,\min }\text{Product}\]
    \[B\xrightarrow{{{t}_{1/2}}=40\,\min }\text{Product}\]
    The temperature coefficients of their reaction rates are 3 and 2, respectively, between \[25{}^\circ C\]and\[35{}^\circ C\]. If the above two reactions are carried out taking \[0.4\text{ }M\]of each reactant but at different temperature: \[25{}^\circ C\] for the first order reaction and \[35{}^\circ C\] for the second order reaction, find the ratio of the concentrations of A and B after an hour.

    A) \[1\]                        

    B)        \[2\]             

    C) \[3\]                       

    D)        \[4\]

    Correct Answer: B

    Solution :

       [b] \[0.4M\] of \[A\xrightarrow{30\,\min }0.2M\xrightarrow{30\,\min }0.1M\] (for A) \[0.4M\]of \[B\xrightarrow{20\,\min }0.2M\xrightarrow{20\,\min }0.1M\xrightarrow{20\,\min }0.05\] (for B) \[\frac{-d[B]}{d}\] will be doubled and hence \[{{t}_{1/2}}\] will be halved \[\therefore \,\,\,\,\frac{[A]}{[B]}=2\]       


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