The amount of radioactive iodine remaining can be calculated using the formula:
Amount = Initial Amount * (1/2)^(t/half-life)
Where:
Amount = Amount remaining after time t
Initial Amount = Starting amount
t = Time elapsed
Half-life = Half-life of the substance
Plugging in the values given:
15.625 = 250 * (1/2)^(t/8)
Dividing both sides by 250:
0.0625 = (1/2)^(t/8)
Taking the natural logarithm of both sides:
ln(0.0625) = (t/8) * ln(1/2)
Solving for t:
t = (8 * ln(0.0625)) / ln(1/2)
t ≈ 64 days
Therefore, 64 days have elapsed between the measurements. The option "64" is correct.
The starting amount of radioactive iodine-131 was 250 g. The half-life is 8 days. When Leslie measured the amount, she measured 15.625 g of radioactive iodine. How many days have elapsed between measurements?
16
24
32
64
1 answer
1 answer