JEE Main & Advanced Sample Paper JEE Main - Mock Test - 10

  • question_answer
    Half-life of a first order reaction is 4 s and the initial concentration of the reactant is\[0.12\text{ }M\]. The concentration of the reactant left after \[16\text{ }s\] is

    A) \[0.0075\text{ }M\]         

    B) \[0.06\text{ }M\]

    C) \[0.03\text{ }M\]              

    D) \[0.015\text{ }M\]

    Correct Answer: A

    Solution :

    \[{{t}_{1/2}}=4s\,\,\,T=16s\] \[n=\frac{T}{{{t}_{1/2}}}=\frac{16}{4}=4\]      \[(\therefore \,\,T=n\times {{t}_{{}^{1}/{}_{2}}})\] \[[A]={{[A]}_{o}}{{\left( \frac{1}{2} \right)}^{n}}=0.12\times {{\left( \frac{1}{2} \right)}^{4}}=\frac{0.12}{16}=0.0075\,M\] Where \[{{[A]}_{o}}\] initial concentration and \[[A]\] = concentration left after time t


You need to login to perform this action.
You will be redirected in 3 sec spinner