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NEET Sample Paper NEET Sample Test Paper-49

  • question_answer
    A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is-

    A) 0.8 ln 2            

    B) 0.4 ln 2

    C) 0.2 ln 2            

    D) 0.1 ln 2

    Correct Answer: B

    Solution :

    \[\lambda \,\,=\,\,\frac{{{\log }_{e}}\frac{{{A}_{1}}}{{{A}_{2}}}}{t}\,\,=\,\,\frac{{{\log }_{e}}\frac{5000}{1250}}{5}\,\,=\,\,0.4\,\,ln\,\,2\]


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