Answer:
half-life=T= 36.9 years
Explanation:
As we know that
N ( t ) = N ( 0 ) ⋅ 0.5 ^(t/ T )
N ( 0 ) =the number of atoms you start with=20 gram
and N ( t )= the number of atoms left=0.625 grams
after a certain time=t=184.5 years
T=half life of a nuclide=?
Putting value in above equation we get
half-life=T= 36.9 years
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