The Maths and Science Tutor
Email: fiaraziqbal@googlemail.com
Phone: 07760257814
Total marks: 20
Time allowed: 25 minutes
[3 marks]
1. A radioactive sample has a mass of 48g. After 6 hours, the mass has decreased to 6g.
a) Calculate the half-life of this sample.
b) What mass will remain after 9 hours?
[2 marks]
2. Explain why alpha radiation is more dangerous if ingested than if it hits your skin from outside your body.
[2 marks]
3. A Geiger counter shows a reading of 240 counts per minute. The background radiation count is 20 counts per minute. Calculate the true count rate in counts per second.
[2 marks]
4. When a nucleus emits a beta particle:
a) What happens to its mass number?
b) What happens to its atomic number?
[2 marks]
5. A smoke detector contains americium-241, which emits alpha particles. Explain how this helps detect smoke.
[2 marks]
6. The count rate from a radioactive source is 80 counts per second at 2 meters from a detector. What would be the count rate at 4 meters from the detector?
[3 marks]
7. Compare and contrast contamination and irradiation. Include one example of each in your answer.
[2 marks]
8. A radioactive isotope decays by emitting an alpha particle followed by a beta particle. Describe what happens to:
a) The mass number
b) The atomic number
[1 mark]
9. Why is lead better than aluminum at shielding against gamma radiation?
[1 mark]
10. Why does the background radiation count vary depending on your geographical location?
End of questions