Final answer:
To calculate the time it takes for the activity of a sample of iodine-128 to drop from 300 to 75, we need to know the half-life of iodine-128.
Step-by-step explanation:
To calculate the time it takes for the activity of a sample of iodine-128 to drop from 300 to 75, we need to use the concept of half-life. The half-life of iodine-128 is not given in the provided information, so we cannot answer the question with the provided information. However, if we knew the half-life of iodine-128, we could use the formula:
t = t₀ x log(initial activity / final activity) / log(2)
Where:
- t is the time it takes for the activity to drop from the initial activity to the final activity
- t₀ is the half-life of the isotope
- initial activity is the initial activity of the sample
- final activity is the final activity of the sample
- log is the logarithm function