Answer :
To determine the time of death of a non-living organic sample that died about an hour ago, you would benefit from using a radioisotope with a half-life that matches or is close to the time frame you are investigating.
Let's examine the options provided:
- Sulfur-35: Half-life of 87.5 days.
- Nitrogen-13: Half-life of 10 minutes.
- Phosphorus-32: Half-life of 14.3 days.
- Hydrogen-3: Half-life of 12.3 years.
- Oxygen-15: Half-life of 122 seconds.
- Carbon-14: Half-life of 5730 years.
Since you are trying to determine an event that occurred about an hour ago, the most relevant isotope would be the one with a half-life closest to that duration.
Nitrogen-13, with a half-life of 10 minutes, is very close to the time frame of interest because it would allow you to monitor changes within short periods accurately. However, since the half-life is quite short, it might decay too quickly for practical observation over an hour.
Oxygen-15, with a half-life of 122 seconds (or just over 2 minutes), decays extremely quickly and would not be practical for measuring an hour's time difference.
Considering these factors, the most appropriate isotope to use would be Nitrogen-13. It decays quickly, which is suitable for very recent events such as the time of death within the last hour.
Therefore, the chosen option is Nitrogen-13 (10 minutes).
To determine the time of death of an organic sample that died just about an hour ago, we need to choose a radioisotope with a half-life that is most suitable for measuring such a short event.
A half-life is the time it takes for half of the radioactive atoms in a sample to decay. If the half-life is too long, it will be difficult to observe any significant decay over such a brief period like an hour. On the other hand, if the half-life is too short, the material may decay too quickly to accurately measure.
By examining the given choices:
Sulfur-35 (87.5 days): This is too long to measure decay over an hour accurately.
Nitrogen-13 (10 minutes): This is short enough to see significant decay changes over an hour since several half-lives will pass in that time.
Phosphorus-32 (14.3 days): This is also too long for the timescale we are looking at.
Hydrogen-3 (12.3 years): This is much too long.
Oxygen-15 (122 seconds): While this is very short and also a good option, it decays too quickly to precisely control and measure depending on the equipment and setup.
Carbon-14 (5730 years): Also too long to measure over an hour.
The best choice for a scenario where we need to pinpoint the death within an hour would be Nitrogen-13 with a half-life of 10 minutes. This can allow precise tracking of decay over multiple half-lives, giving a clear indication of the time past after an hour has elapsed, which suits the scenario perfectly. So, the correct choice is: Nitrogen-13 (10 minutes).
