Question

If only one-eighth of the sodium-24 remains, roughly how many hours have elapsed, given its half-life is approximately 15 hours?(1 point)
Responses

45 hours
45 hours

30 hours
30 hours

60 hours
60 hours

15 hours

Answers

GPT-4o mini
The half-life of sodium-24 is 15 hours. To determine how many half-lives it takes for only one-eighth of the original amount to remain, we can use the following:

1. One half-life reduces the amount to half (1/2).
2. Two half-lives reduce it to one-quarter (1/4).
3. Three half-lives reduce it to one-eighth (1/8).

So, it takes three half-lives to go from the original amount to one-eighth of the amount.

Given that each half-life is 15 hours:

Total time = 3 half-lives × 15 hours/half-life = 45 hours.

Therefore, the answer is **45 hours**.