Half life of 238U (t1/2) = 4.5× 109 years .
Initial amount of 238U = 5.0 Kg.
Final amount = 2.5 Kg.
Amount of 238U decayed = (5.0 - 2.5) Kg = 2.5 Kg
So, 238U has passed one halflife.
So time taken = 4.5 × 109 years.
Mass number of Pb = 206
Mass number of U = 238
Now, 206 g Pb is formed by 238 g U.
Or, 206 Kg Pb is formed by 238 Kg of U
Hence,
amount of Lead produced when 2.5 Kg Uranium is decayed
= 2.5 Kg U ×
= 2.16 Kg Pb.
2. Using the decay chain for 238U, calculate the amount of time it takes 5.0 kg...
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