Question

ess of radioactive decay. You will examine how long it takes for an isotope to decay. In the space below, write a scientific question that you will answer by doing this experiment.

How long does it take for 90% of a sample of the simulated isotope to decay (i.e., for the remaining activity to drop to 10% of its initial value)?

Independent variable: time
Dependent variable: fraction (or percent) of nuclei remaining/decayed
Controls: initial number of atoms, temperature and simulation decay constant/settings
Sample Response: How does the number of radioactive atoms change over time?

What did you include in your question? Check all that apply.

a change in the number of radioactive atoms
time
a connection between time and the number of radioactive atoms

Answer 1

All three.

- a change in the number of radioactive atoms — yes (asks about 90% decaying).
- time — yes (“How long does it take…”).
- a connection between time and the number of radioactive atoms — yes (asks how long for the fraction remaining to reach 10%).