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Home / Doubts and Solutions/NEET/Physics

please answer this

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Asked by Prashant DIGHE 10th January 2020, 10:07 PM
Answered by Expert
Answer:
decay constant λ = ln2 / T1/2 = 0.693 / 1386 = 5×10-4 s-1
 
Radioactivity equation,  N = No e-λt
 
Fraction of undecayed sample after 80 s = N / No =  exp( - 5 × 10-4 × 80 ) = 0.96
 
Hence fraction of number of nuclei that has decayed in initial 80 s = 1 - 0.96 = 0.04
 
Hence fraction of number of nuclei ( expressed in % ) that has decayed in initial 80 s = 4 %
Answered by Expert 10th January 2020, 10:56 PM
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