EXAM QUESTIONS FOR RADIOISOTOPES
100 points total
1. (6 pts) What is the difference between atomic number and mass number? Which
of these two numbers determines the IDENTITY OF AN ELEMENT?
2. (4 pts) How can the process of nuclear disintegration result in the change of the
IDENTITY of an element? Be specific.
3. (4 pts) What is an isotope?
4. (4 pts) What is a radioisotope?
5. (16 pts) Circle the correct response:
a.) TRUE / FALSE: All types of radiation are external hazards.
b.) TRUE / FALSE: All types of radiation are internal hazards.
c.) TRUE / FALSE: -particles are more penetrating because they are larger
particles than alpha particles
d.) TRUE / FALSE: -particles are less hazardous to work with because they
do not penetrate the layer of dead skin of the body
e.) TRUE / FALSE: gamma rays are the most penetrating form of radiation
f.) TRUE / FALSE: When working with beta-emitters, you must always use
Lucite shielding
g.) TRUE / FALSE: -particles are the most serious internal hazard to the body
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h.) TRUE / FALSE: When a radioisotope releases an -particle, that isotope
turns into a different element.
6. (6 pts) You are going to be doing an experiment involving radioactivity. Your coworker is telling you about your likely level of exposure. Is it more useful for him to
provide you that information in rad or rem? EXPLAIN WHY THE UNIT YOU
HAVE CHOSEN IS MORE USEFUL.
7. (4 pts) What is a “physical half-life”?
8. (4 pts) Suppose you start with 1000 atoms of a radioisotope with a half-life of 7 days
on February 1st. How many atoms of radioisotope will remain on March 1st? SHOW
YOUR WORK.
9. (4 pts) What is meant by the ACTIVITY of a radioactive sample?
10. (8 pts) What is the difference between a “stochastic” versus a “non-stochastic” effect
of radiation exposure? Provide ONE example of each type of effect.
11. (4 pts) What is a BIOLOGICAL HALF-LIFE?
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12. (6 pts) Suppose you accidentally ingest a radioisotope. Provide TWO factors that
will affect how much damage this ingestion does to your body.
13. (5 pts) Provide TWO assumptions about the current no-threshold model of risk
assessment that make it likely that the calculated risks associated with working with low
levels of radioactivity are an OVERESTIMATE of the true risks.
14. (10 pts) Suppose you receive a dose of 16 rad from a source that is positioned 1 foot
from you. How many rad will you receive if you move to a distance that is 4 feet from
the source?
15. (5 pts) Suppose you are going to work with an alpha emitter. What type of shielding
is required?
16. (5 pts) Suppose you are going to work with a high energy beta emiiter. What type of
shielding is required?
17. (5 pts) Considering the REASON that radiation is damaging, what is the purpose of
using shielding? (Why does it protect the worker?)
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