Question Detail
Question
The table shows the results of an experiment to find the half-life of a radioactive substance. What estimate of the half-life of the isotope can be obtained from the readings in the table?
| Time (hours) | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|
| Corrected count rate (counts/s) | 800 | 620 | 480 | 370 | 290 | 220 |
Correct Answer
Option B is the correct answer.
Detailed Explanation
The half-life of a radioactive substance is the time it takes for the activity (or count rate) to reduce to half of its initial value.The initial count rate at time = 0 hours is 800 counts/s.Half of the initial count rate is 800 / 2 = 400 counts/s.Now, let's look at the table to find when the count rate is 400 counts/s:- At 2 hours, the count rate is 480 counts/s.- At 3 hours, the count rate is 370 counts/s.Since 400 counts/s is between 480 and 370, the half-life must be between 2 hours and 3 hours.
Hint
Identify the initial count rate and then determine what half of that value is. Locate this halved value within the given data range.