NUCLEAR PHYSICS TEST 2006
Name:
MULTIPLE CHOICE
Circle the best response:
1.
How many protons, neutrons and nucleons are in the
A
25, 20, 45
2.
95
An atom of molybdenum 42
Mo has in its nucleus
B
A 42 protons only
B
D 42 protons and 53 neutrons E
20, 25, 45
C
45
20 Ca?
25, 45, 20
D
45, 20, 25
42 neutrons only
C
42 protons and 42 neutrons
95 protons and 42 neutrons
F
53 protons and 42 neutrons
3.
An alpha particle consists of
A
2 protons and 2 electrons
B
4 protons
C
2 protons and 2 neutrons
D
2 neutrons and 2 electrons
4.
The radiation which is the least powerful ioniser is?
A gamma rays
B
neutrons
C
alpha particles
D
beta particles
5.
Which one of the following best describes the relative speeds at which alpha, beta, and gamma
particles travel after being emitted from radioisotopes?
A Alpha is the slowest, beta and then gamma
B
Beta is the slowest, gamma and then alpha
C Gamma is the slowest, alpha and then beta
D
Gamma is the slowest, beta and then alpha
C
alpha particles
6.
Which radiation has no mass or charge
A gamma rays
B
neutron
D
beta particles
7.
When tellurium-130 ( 130
52 Te) is bombarded with neutrons (inside the core of a nuclear reactor) it
forms a very unstable tellurium-131 and a gamma ray. The equation for this process is
A
130
52 Te
C
130
52 Te

131
52 Te
+ 01 n 
+ 01 n + 
131
52 Te
+
131
52 Te
B
130
52 Te

D
130
52 Te
+ 2 01 n 
+ 2 01 n + 
131
52 Te
+
8
When an atom undergoes -decay
A
The mass number increases by 1 and the atomic number is constant
B
The mass number decreases by 4 and the atomic number decreases by 2
C
The mass number decreases by 2 and the atomic number decreases by 4
D
The mass number is constant and the atomic number increases by 1
9. When an atom undergoes -decay
A
The mass number decreases by 2 and the atomic number decreases by 4
B
The mass number is constant and the atomic number increases by 1
C
The mass number decreases by 4 and the atomic number decreases by 2
D
The mass number increases by 1 and the atomic number is constant
10.
A radioactive source emits one type of radiation only. On investigation it is found that the rays will
penetrate quite well through 1mm of aluminium, but will not penetrate 1cm of lead. The radiation
emitted will most probably be
A
beta particles
11.
A radioactive substance has a half-life of 1 minute. How long does it take for the activity of a sample
of this substance to fall to one-eighth of its original value?
A
3 minutes
B alpha particles
B
C
infrared rays
4 minutes
C
D
8 minutes
D
gamma rays
16 minutes
223
12.
88 Ra has a half-life of 12 days. If a mass of M kg of this isotope is initially present, the amount
remaining after 48 days will be
A
1
2
M kg
B
1
4
M kg
C
1
8
M kg
D
1
16
M kg
13.
Thorium has a half-life of 24 days. How many days would it take for 8 gm thorium to disintegrate to
1 gm.
A
3
B
24
C
72
D
96
14.
When a 228
90 Th nucleus undergoes radioactive decay by the emission of an alpha particle the new
nucleus formed is
A
228
89 Ac
B
228
90 Ac
C
234
88 Ra
D
224
87 Fr
SHORT ANSWER
Question 1
Carbon Dating is a technique used to determine the age of organic material. The activity (rate of decay) of
14C atoms in the sample is measured. 14C has a half life of 5730 years.
a) Explain how the activity of 14C in an organic sample can be used to determine its age.
b)
Carbon dating is only effective for objects that are less than 60,000 years old. Explain why this is the
case
Archeologist in South Australia have dug up a spear during an excavation at an aboriginal site. They
measure the rate of decay of 14C in 2g of the wood to be 5 MBq. A 2g sample of modern wood has a decay
rate of 40 MBq.
b)
Determine the approximate age of the wood sample
Question 2
Radiation is known to have long-term and short-term effects on the body.
a) List two short term effects of exposure to large amounts of radiation
b) Radiation can cause long-term damage to the body. What does the radiation do to the body to cause
these long-term effects long after the radiation is gone?
c)
The “quality Factors” of Alpha, Beta and Gamma radiation are 20, 1 and 1 respectively. What is
meant by the term “Quality Factor” and why is it used when determining your dose equivalent?
d)
A
B
C
e)
A
B
C
Which of the following is the most damaging radiation dose? Use the values from part c) if you think
they are relevant
200Gy of gamma radiation
20 Gy of alpha radiation
50 Gy of beta radiation
Which of the following is the most damaging radiation dose? Use the quality factors from part c) if
you think they are relevant.
200 Sv of gamma radiation
20 Sv of Alpha radiation
50 Sv of beta radiation
Question 3
The radio-isotope Technetium-99m is commonly used in Medical imaging in Hospitals. It can be produced in
two ways. The first method requires a nuclear reactor. The Technetium-99m is produced in the reactor and
then must be transported to the hospital where it is used.
99m
43
Tc has a half life of 6 hours.
a) If the technetium is shipped from Lucas heights in Sydney to Melbourne it will arrive 6 hours. What
fraction of the original sample of radioisotope is left after this time?
b) If the technetium is shipped in from America, it will arrive in 30 hours. What fraction of the original
sample of radioisotope is left after this time?
Technetium-99m can also be produced from the radioactive decay of Molybdenum-99. This decay is shown
in the equation below
99
42
a)
m
Mo  9943
Tc  X
What is the particle X?
The decay of Molybdenum to technetium-99m occurs with a half life of 60 hours. The Molybdenum must be
reordered when approximately 12.5% of the original amount remains.
b)
How often does the Molybdenum need to be re-ordered?