NEET Sample Paper NEET Sample Test Paper-88

  • question_answer
    \[{{T}_{50}}\] of first -order reaction is 10 min. Starting with \[10\,mol\,{{L}^{-1}}\] rate after 20 min is

    A) \[0.0693\,mol\,{{L}^{-1}}\,{{\min }^{-1}}\]

    B) \[0.0693\times 2.5\,mol\,{{L}^{-1}}\,{{\min }^{-1}}\]

    C) \[0.0693\times 5\,mol\,{{L}^{-2}}\,{{\min }^{-1}}\]

    D) \[0.0693\times 10\,mol\,{{L}^{-1}}\,{{\min }^{-1}}\]

    Correct Answer: B

    Solution :

    [b] Initial concentration \[=10\,\,mol\,\,{{L}^{-1}}\] \[\therefore \] Cone. after 20 min (two half-lives) \[=2.5\,mol\,\,{{L}^{-1}}\] Now, \[k=\frac{0.693}{{{t}_{1}}/2}=\frac{0.693}{10\min }\] or   \[0.0693\,{{\min }^{-1}}\] \[\therefore \]  rate \[=k\times \] [reactant] \[=0.0693\times 2.5\,mol\,\,{{L}^{-1}}\,\,{{\min }^{-1}}\]


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