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JEE Main & Advanced Chemistry Chemical Kinetics / रासायनिक बलगतिकी Question Bank Rate law and Rate Constant

  • question_answer
    In the first order reaction, the concentration of the reactant is reduced to 25% in one hour. The half life period of the reaction is           [DCE 2004]

    A)                 2 hr       

    B)                 4 hr

    C)                 1/2 hr   

    D)                 1/4 hr

    Correct Answer: C

    Solution :

               \[K=\frac{2.303}{1\ hr}\log \frac{100}{25}=\frac{2.303}{t}\log \frac{100}{50}\]                    \[\therefore \ \ \log 4=\frac{1}{t}\log 2\]                                 \[\therefore \ \ 2\log 2=\frac{1}{t}\log 2\]; \[t=\frac{1}{2}hr\].  


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