10 minutes maximum! (can you do it in 5?)


1. Which of these is the best description of the 'activity' of a radioactive rock?
 A. The total number of radioactive atoms that have decayed.
 B. The total number of radioactive atoms remaining undecayed in the rock.
 C. The number of gamma rays emmited per second.
 D. The number of radioactive atoms that have decayed per second.


2. What are the units used to measure the Activity of a sample of rock?
 A. coulombs (C)
 B. becquerels (Bq)
 C. joules (J)
 D. watts (W)



Q36.
The graphs below show 4 ways the count rate from a radioactive isotope could change:

3. Which of the above graphs shows the correct shape for radioactive decay? 

4. Using the correct graph, what is the half life of the sample?
 A. 5 years
 B. 10 years
 C. 20 years
 D. 40 years


5. What is the activity of the sample after 2 half lifes?
 A. 800 counts per second
 B. 400 counts per second
 C. 200 counts per second
 D. 0 counts per second


6. Use the correct graph to estimate the count rate after 30 years.
 A. 100 counts per second
 B. 200 counts per second
 C. 25 counts per second
 D. 550 counts per second


Q710: An isotope has a half life of 8 hours.
7. How much of the sample will remain after 24 hours?
 A. ^{1}⁄_{2}
 B. ^{1}⁄_{3}
 C. ^{1}⁄_{4}
 D. ^{1}⁄_{8}



8. If the mass of the isotope is 12 g of pure radioactive isotope, how many grams remains after 16 hours?
 A. 0.75 g
 B. 3 g
 C. 4 g
 D. 6 g


9. What has happened to the rest of the mass of the isotope?
 A. All converted to radiation
 B. All converted to heat energy.
 C. Converted into a new element.
 D. remained the same isotope but evaporated.


10. Here are three suggestions for safe use for the isotope:
Which of these are realistic and sensible suggestions?
 A. II only
 B. I and II
 C. II and III
 D. All three

I. Do not handle directly  use tongs.
II. Store in a thick lead or steel box.
III. Do not look directly at the isotope whilst handling it. 

