Question

You have 84,000 grams of a radioactive kind of tellurium. How much will be left after 75

minutes if its half-life is 25 minutes?
grams

Answer 1

10,500 g

Explanation:

Half-life is the length of time it takes for half of the radioactive atoms of a radionuclide to decay. In this scenario, the amount of radioactive atoms is halved after 25 minutes. After 75 minutes, then, the amount of radioactive atoms is halved three times. Therefore:

1st half-life:
`84000\text{ g}/{2}=42000\text{ g}`

2nd half-life:
`42000\text{ g}/{2}=21000\text{ g}`

3rd half-life:
`21000\text{ g}/{2}=10500\text{ g}`