Final answer:
After 116 years, which corresponds to four half-lives of Strontium-90 with a half-life of 29 years, approximately 125 kg of the initial 2000 kg of Strontium-90 would remain.
Step-by-step explanation:
To calculate the mass of Strontium-90 left after 116 years, we can apply the concept of half-life and the exponential decay formula. Strontium-90 has a half-life of approximately 29 years (closely rounded from 28.8 years given in source material). After 116 years, 4 half-lives will have passed (since 116 / 29 = 4).
Using the expression for the remaining mass after a given number of half-lives:
- Initial mass = 2000 kg
- After 1 half-life: 50% remains, so mass is 1000 kg
- After 2 half-lives: 25% remains, so mass is 500 kg
- After 3 half-lives: 12.5% remains, so mass is 250 kg
- After 4 half-lives: 6.25% remains, so mass is 125 kg
Therefore, approximately 125 kg of Strontium-90 would be left after 116 years.