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NEET Sample Paper NEET Sample Test Paper-91

  • question_answer
    After 300 days, the activity of a radioactive sample is 5000 dps (disintegrations per sec). The activity becomes 2500 dps after another 150 days. The initial activity of the sample in dps is

    A) 20,000 

    B)        10,000

    C) 7,000   

    D)        25,000

    Correct Answer: A

    Solution :

    [a] Activity decreases 5000 dps to 2500 dps in 150 days \[\therefore \] Half life period \[{{T}_{1/2}}=150\,days\] \[\therefore \]300 days \[=2{{T}_{1/2}}\] Therefore, initial activity\[=5000\times 2{{T}_{1/2}}\] \[=5000\times 2\times 2=20000\,dps\]


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