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NEET Chemistry NEET PYQ-Chemical Kinetics

  • question_answer
    The rat e of a first -order react ion is \[\text{0}\text{.04}\,\text{mol}\,{{\ell }^{-1}}{{s}^{-1}}\]at 10 seconds and \[0.03\,\text{mol }{{\ell }^{-1}}{{s}^{-1}}\]at 20 seconds after initiation of the reaction. The half-life period of the reaction is:                                           [NEET - 2016]

    A) 24.1 s

    B) 34.1 s

    C) 44.1 s

    D) 54.1 s

    Correct Answer: A

    Solution :

    [a] \[K=\frac{2.303}{({{t}_{2}}-{{t}_{1}})}\log \left( \frac{a-{{x}_{1}}}{a-{{x}_{2}}} \right)\]
                \[K=\frac{2.303}{(20-10)}\log \left( \frac{0.04}{0.03} \right)\]
                \[K=\frac{2.303\times 0.1249}{10}\]
                \[\frac{2.303\times \log 2}{{{t}_{1/2}}}=\frac{2.303\times .1249}{10}\]
                \[{{t}_{1/2}}=\frac{0.3010\times 10}{0.1249}=24.1\,\sec \]


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