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NEET-XII-Physics

13: Nuclei

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  • #10
    The half-life of is 28 years. What is the disintegration rate of 15 mg of this isotope?
    Ans : Half life of , = 28 years

    = 28 × 365 × 24 × 60 × 60

    = 8.83 × 108 s

    Mass of the isotope, m = 15 mg

    90 g of atom contains 6.023 × 1023 (Avogadro’s number) atoms.

    Therefore, 15 mg of contains:



    Rate of disintegration,

    Where,

    λ = Decay constant



    Hence, the disintegration rate of 15 mg of the given isotope is 7.878 × 1010 atoms/s.