QUESTION I. Briefly, define the following terms:
1.
Half-life
2.
Radiometric Dating
3.
Becquerel (Bq)
4.
Radiometric survey
MASTER Page 1 of 5
(
QUESTION II.
A)
228
B)
A rock has a radioactive parent/daughter ratio of 1:31, given that the half-life of the
radioactive element is 57 million years, how old is the rock. Use the figure below.
Ac has a half-life of 6.13 hours. How much of a 50 gram sample of this element will
be left after 2 days?
MASTER Page 2 of 5
C) Use the table below to make a comparison between gamma and beta emissions:
Emission
Property
Gamma
Beta
Type of charge
Ionization
Penetration
QUESTION III Answer the following by filling False or True in the brackets
1. The emission of Gamma ray (γ) accompanies always the K capture process.
(
2. Radioactive decay of the actinium series produces the unstable isotope of lead (Pb).
)
)
(
3. Man-borne radioactive survey is mainly used in preliminary radioactive investigations.(
)
4. Quality control of radioactive measurements should be done immediately on site.
(
)
5. Alpha particles are widely used in radiometric prospecting surveys.
(
)
6. The equipment commonly used in recent radiometric surveys is the count meter.
(
)
7. Phosphate has stronger radioactivity than dolomite.
(
)
8. Interpretation of radioactive survey measurements is done in the form of total or spectral
gamma ray intensity profile maps.
(
)
MASTER Page 3 of 5
QUESTION IV Circle the letter corresponding to the best answer:
1. In 92U234, the number of neutrons is
A. 234
B. 326
C. 92
D. 142
2. The three radioactive elements that are most significant in radiometric prospecting are:
A. Lead, uranium and potassium
B. Potassium, uranium and thorium
C. Potassium, rubidium and uranium
D. Uranium, potassium and lithium.
3. The radioactive rate of change is:
A. Affected by physical processes
B. Proportional to the number of atoms present
C. Affected by chemical processes
D. All of the above
4. Polonium-212 (84Po212) decays by α emission. What is the decay product?
A. 82Pb208
B. 83Bi212
C. 98Ac228
D. 84Po215
5. The time interval for making a measurement at a measurement point in a man-borne
radioactive survey is:
A. 5 – 25 seconds
B. 2- 7 seconds
C. 60 – 65 seconds
D. 300 – 500 seconds
6. The major field(s) of application of a radiometric survey:
A. Characterization of active faults
B. Hot spring development
C. Both “A” and “B”
D. None of the above
MASTER Page 4 of 5
QUESTION V
Given that:
Show that:
Where:
: is decay constant
: is original quantity of atoms at time, t = 0
: is the remaining quantity at time t
: is the half-life time
MASTER Page 5 of 5