Question

You have 8,560 grams of a radioactive kind of rubidium. If its half-life is 15 minutes, how

much will be left after 45 minutes?
grams

Answer 1

1,070 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 15 minutes. After 45 minutes, then, the amount of radioactive atoms is halved three times. Therefore:

1st half-life: 8,560 ÷ 2 = 4,280 g

2nd half-life: 4,280 ÷ 2 = 2,140 g

3rd half-life: 2,140 ÷ 2 = 1,070 g