The main aim of this scenario is to find out the relationship between half-life of given radionuclide and it's quantity. To reveal such dependence, the absolute determination of activity is required, which is represented by correction of the count rate on thickness (attenuation) of the measured sample.

1. Nuclear chemistry learning objectives. The user will:
   • Understand the relationship between activity and the amount of the radionuclide.
   • Understand the difference between activity and the measured count rate or counts, and the meaning of the efficiency of the measurement.
   • Understand what is (self) attenuation of the radiation in the sample.
   • Learn what is the shape of the count rate versus mass curve and reasoning of such a shape.
2. VR-Lab learning objectives. The user will learn:
   • How to weight and dose specific amount of powder in the VR-Lab
   • How to operate gamma detector and how to measure samples.

This scenario is composed of four Quests, namely:

1. Preparation
2. Weighting and activity measurement
3. Evaluation of the results and
4. Cleaning the workplace

The difficulty is rather low and user shall be able to finish it in 30 minutes. Feel free to experiment with different amounts of the radiochemical or short and long detection times. How will lower/higher background radioation affect the results?