# Worksheet: Radioactive Decay

In this worksheet, we will practice calculating the activity of a radioactive sample after a given amount of time using the half-life of the isotope.

**Q1: **

A radioactive sample initially contains mol of a radioactive material which has a half-life of 6.00 hours.

Approximately how many moles of the radioactive material remain after 6.00 h?

- A mol
- B mol
- C mol
- D mol
- E mol

Approximately how many moles of the radioactive material remain after 12.00 h?

- A mol
- B mol
- C mol
- D mol
- E mol

Approximately how many moles of the radioactive material remain after 36.00 h?

- A mol
- B mol
- C mol
- D mol
- E mol

**Q2: **

A sample of radioactive material is obtained from a very old rock.
A plot of the natural logarithm
of the sample’s activity versus time yields
a slope value of
s^{−1}.
What is the half-life of this material?

- A years
- B years
- C years
- D years
- E years

**Q3: **

A piece of wood from an ancient Egyptian tomb is tested for its carbon-14 activity. It is found to have an activity per gram decay/ming.
What is the age of the wood? Use a value of s^{−1} for the decay constant of carbon-14 and a value of for the relative abundance of carbon-14.