2. Solved Papers
  3. NEET

NEET NEET SOLVED PAPER 2017

  • question_answer
    Radioactive material 'A' has decay constant \['8\lambda '\]and material 'B' has decay constant \['\lambda '.\] Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be \[\frac{1}{e}\]?

    A)  \[\frac{1}{9\lambda }\]                                

    B) \[\frac{1}{\lambda }\]

    C)  \[\frac{1}{7\lambda }\]                                

    D)  \[\frac{1}{8\lambda }\]

    Correct Answer: C

    Solution :

                     No option is correct If we take \[\frac{{{N}_{A}}}{{{N}_{B}}}=\frac{1}{e}\] Then                                 \[\frac{{{N}_{A}}}{{{N}_{B}}}=\frac{{{e}^{-8\lambda t}}}{{{e}^{-\lambda t}}}\] \[\frac{1}{e}={{e}^{-7\lambda t}}\] \[-1=-7\lambda t\] \[t=\frac{1}{7\lambda }\]


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