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## Approximately how many radioactive atoms are present in a tritium sample with an activity of 0'4 x 1

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### Approximately how many half-life periods must elapse if the activity of a ... 3. 2. 1. 3. 6. 8. 60. Tritium has a half-life of 12.3 years. ... – PowerPoint PPT presentation

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Title: Approximately how many radioactive atoms are present in a tritium sample with an activity of 0'4 x 1

1
Approximately how many radioactive atoms are
present in a tritium sample with an activity of
0.4 x 10-6 Ci and a half-life of 12.3 years? (1
Ci 3.7 x 1010 decays/s)
• 13 x 107
• 7 x 108
• 3 x 1010
• 8 x 1012

2
What is the binding energy per nucleon of Au-197
(atomic number 79)? (The following information
regarding atomic masses will be needed Au-197,
196.966560 hydrogen, 1.007825 neutron,
1.008665 also 1 u x c2 931.5 MeV)
• 7.3 MeV
• 7.7 MeV
• 7.9 MeV
• 8.3 MeV

3
Approximately how many half-life periods must
elapse if the activity of a radioactive isotope
sample is to be reduced to 0.004 of the original
value?
• 3
• 6
• 8
• 60

4
Tritium has a half-life of 12.3 years. What
proportion of its original radioactivity will a
sample have after 9 years?
• 0.55
• 0.60
• 0.73
• 0.84

5
The activity of a newly discovered radioactive
isotope reduces to 96 of its original value in
an interval of 2 hours. What is its half-life?
• 10.2 hrs
• 34.0 hrs
• 44.0 hrs
• 68.6 hrs

6
If there are 128 neutrons in Pb-210, how many
neutrons are found in the nucleus of Pb-206?
• 122
• 124
• 126
• 130

7
The existence of the neutrino was postulated to
account for which basic conservation laws during
the beta decay process?
• conservation of energy
• conservation of momentum
• both of the choices are valid
• none of the choices are valid

8
A radioactive isotope which emits a gamma quantum
will change in what respect?
• atomic number increases by one
• atomic number decreases by one
• atomic mass number decreases by one
• none of the choices are valid

9
A radioactive isotope which emits an alpha
particle will change in what respect?
• atomic number decreases by four
• mass number decreases by four
• both atomic number and mass number decrease by
four
• none of the choices are valid

10
Tritium has a half-life of 12.3 years. How many
years will elapse when the radioactivity of a
tritium sample diminishes to 10 of its original
value?
• 31 years
• 41 years
• 84 years
• 123 years

11
A pure sample of Ra-226 contains 2.0 x 1014 atoms
of the isotope. If the half-life of Ra-226 1.6
x 103 years, what is the decay rate of this
sample? (1 Ci 3.7 x 1010 decays/s)
• 2.7 x 10-12 Ci
• 3.4 x 10-10 Ci
• 7.5 x 10-8 Ci
• 9.6 x 10-6 Ci

12
What energy must be added or given off in a
reaction where one hydrogen atom and two neutrons
are combined to form a tritium atom? (atomic
masses for each hydrogen, 1.007825 neutron,
1.009665 tritium, 3.016049 also, 1 u x c2
931.5 MeV)
• 8.5 MeV given off
• 10.3 MeV given off

13
An ancient building was known to have been built
3000 years ago. Approximately what proportion of
C-14 atoms are yet in the building's wooden
framing compared to the number which were present
at the time of its construction? (half life of
C-14 5800 years)
• 0.425
• 0.500
• 0.517
• 0.698

14
The isotope Zn-64 has a nuclear radius of 4.8 x
10-15 m. Which of the following is the mass
number of an isotope for which the nuclear radius
is 7.2 x 10-15 m?
• 144
• 96
• 125
• 216

15
A pure sample of Ra-226 contains 2 x 1014 atoms
of the isotope. If the half-life of Ra-226 1.6
x 103 years, what is the decay rate of this
sample?
• 6.7 x 109 decays/yr
• 8.7 x 1010 decays/yr
• 9.4 x 1010 decays/yr
• 12.6 x 10-10 decays/yr

16
The beta emission process results in the daughter
nucleus differing in what manner from the parent?
• atomic mass increases by one
• atomic number decreases by two
• atomic number increases by one
• atomic mass decreases by two

17
The gamma radiation first detected by Becquerel
was in fact which of the following?
• helium nuclei
• high energy quanta
• electrons
• positrons

18
The alpha emission process results in the
daughter nucleus differing in what manner from
the parent?
• atomic mass increases by one
• atomic number decreases by two
• atomic number increases by one
• atomic mass decreases by two

19
If the sum total mass of reactants in a nuclear
reaction is greater than that of product
particles, then which of the following statements
best describes the conditions of the reaction?
• reaction is exothermic
• reaction is endothermic
• atomic number of each reactant must be greater
than 40
• atomic number of each reactant must be less than
80

20
The isotope Zn-64 has a nuclear radius of 4.8 x
10-15 m. Approximately what is the nuclear radius
of an isotope of Al-27?
• 2.0 x 10-15 m
• 2.7 x 10-15 m
• 3.6 x 10-15 m
• 4.0 x 10-15 m

21
The ratio of the numbers of neutrons to protons
in the nucleus of naturally occurring isotopes
tends to vary with atomic number in what manner?
• increases with greater atomic number
• decreases with greater atomic number
• is maximum for atomic number 60
• remains constant for entire range of atomic
numbers

22
The atomic mass number of a nucleus is equivalent
to which of the following numbers?
• neutrons present
• protons present
• difference in neutron and proton numbers
• sum of neutron and proton numbers

23
Of the main types of radiation emitted from
naturally radioactive isotopes, which of the
following is the most penetrating?
• alpha
• beta
• gamma
• positron

24
Samples of two different isotopes, X and Y, both
contain the same number of radioactive atoms.
Sample X has a half life twice that of Y. How do
• X has a greater rate than Y
• X has a smaller rate than Y
• rates of X and Y are equal
• rate depends on atomic number, not half life

25
The beta radiation first detected by Becquerel
was in fact which of the following?
• helium nuclei
• high energy quanta
• electrons
• positrons

26
The alpha radiation first detected by Becquerel
was in fact which of the following?
• helium nuclei
• high energy quanta
• electrons
• positrons

27
The atomic number of a given element is
equivalent to which of the following?
• proton number in the nucleus
• neutron number in the nucleus
• sum of the protons and neutrons in the nucleus
• number of electrons in the outer shells

28
Chromium-55 (54.9279 u) emits an electron (0.0005
u) leaving a daughter nucleus of manganese-55
(54.9244 u). How much energy is released in this
reaction? (1 u x c2 931 MeV)
• 5.59 MeV
• 2.79 MeV
• 1.40 MeV
• 0.70 MeV

29
An endothermic nuclear reaction occurs as a
result of the collision of two reactant nuclei.
If the Q value of this reaction is -2.17 MeV,
which of the following describes the minimum
kinetic energy needed in the reactant nuclei if
the reaction is to occur?
• equal to 2.17 MeV
• greater than 2.17 MeV
• less than 2.17 MeV
• exactly half of 2.17 MeV

30
If a fossil bone is found to contain 1/8th as
much Carbon-14 as the bone of a living animal,
what is the approximate age of the fossil?
(half-life of C-14 5800 years)
• 8,000 years
• 17,400 years
• 23,000 years
• 46,400 years

31
Rutherford's experiments involving the use of
alpha particle beams directed onto thin metal
foils demonstrated the existence of which of the
following?
• neutron
• proton
• nucleus
• positron

32
The components of natural radiation, in order of
least to most penetrating, are which of the
following choices?
• alpha, beta and gamma
• gamma, beta and alpha
• beta, gamma and alpha
• alpha, gamma and beta

33
A radioactive material initially is observed to
have an activity of 800 counts/sec. If four hours
later it is observed to have an activity of 200
counts/sec, what is its half life?
• 1 hour
• 2 hours
• 4 hours
• 8 hours

34
The experiment which gave the first evidence for
the existence of the atomic nucleus involved
which of the following?
• X-ray scattering
• cosmic ray detection
• alpha scattering

35
The nucleus of an atom is made up of which of the
following?
• electrons and protons
• electrons and neutrons
• protons, electrons and neutrons
• protons and neutrons

36
of the following?
• beta
• alpha
• gamma
• positron

37
When bismuth-214 emits a beta particle, the
remaining daughter nucleus is which of the
following?
• actinium-215
• polonium-214
• bismuth-215

38
Certain stars at the end of their lives are
thought to collapse combining their protons and
electrons together to form a neutron star. Such a
star could be thought of as a giant atomic
nucleus. If a star of mass equal to that of the
sun (M 2 x 1030 kg) collapsed into neutrons (mn
1.67 x 10-27 kg), what would be the radius of
such a star? (HINT r r0A1/3)
• 25.4 km
• 18.7 km
• 12.7 km
• 6.4 km

39
Calculate the binding energy of the tritium
nucleus, given that the mass of the tritium
nucleus is 3.01605 u. (mp 1.007276 u, mn
1.008665, and 1 u 931.5 MeV/c2)
• 2.24 MeV/nucleon
• 2.45 MeV/nucleon
• 2.66 MeV/nucleon
• 2.86 MeV/nucleon

40
The half-life of radioactive iodine-131 is 8
days. Find the number of 131I nuclei necessary to
produce a sample of activity 1.0µ Ci. (1 Curie
3.7 x 1010 decays/second)
• 4.6 x 109
• 3.7 x 1010
• 7.6 x 1012
• 8.1 x 1013

41
How much kinetic energy must an alpha particle
(charge 2 x 1.6 x 10-19 C) have to approach to
within 10-14 m of a gold nucleus (charge 79 x
1.6 x 10-19 C)? k 9 x 109 N-m2 /C2 and 1 MeV
1.6 x 10-13 J
• 11.70 MeV
• 14.55 MeV
• 18.15 MeV
• 22.75 MeV

42
Tritium is radioactive with a half-life of 12.33
years decaying into with low-energy
electron emission. If we have a sample of 3 x
1018 tritium atoms, what is its activity in
decays/second? (1 year 3.15 x 107 s)
• 4.20 x 1010/second
• 5.35 x 109/second
• 3.69 x 108/second
• 6.64 x 107/second

43
An alpha particle (mass 6.68 x 10-27 kg) is
emitted from a radioactive nucleus with an energy
of 5 MeV. How fast is the a-particle moving in
m/s? (1 MeV 1.6 x 10-13 J)
• 2.40 x 107 m/s
• 1.55 x 107 m/s
• 3.70 x 106 m/s
• 1.85 x 106 m/s

44
A 1-gram sample of petrified wood is taken from a
petrified forest. If the Carbon-14 activity of
the sample is 12.5 that of present-day organic
material, what is the age of the petrified wood?
(T1/2 for C-14 is 5,730 years)
• 4,460 years
• 8,600 years
• 13,150 years
• 17,200 years

45
In the beta decay of 14C, the existence of the
anti-neutrino was required to maintain?
• energy conservation.
• charge conservation.
• conservation of the number of nucleons.
• all of the choices

46
The fact that the binding energy per nucleon
doesn't depend very strongly on the volume of the
nucleus indicates that?
• the strong nuclear force saturates.
• nucleons don't move throughout the nucleus.
• all nuclei have the same volume.
• the radius of a nucleus is directly proportional
to the number of nucleons.

47
According to the shell model of the nucleus,
radioactive decay which produces beta rays occurs
because?
• there is a vacant energy level for a neutron and
as a neutron drops down to this lower energy
level it gives up its energy to an electron.
• there is no vacancy in a neutron energy level so
the neutron goes to an energy level previously
occupied by an electron.
• the neutron must change to a proton before it can
go to a lower energy level.
• the neutron gets rid of excess angular momentum
by giving it to ejected electron.

48
Some nuclei are not spherical and this can best
be explained by the?
• liquid drop model.
• shell model.
• collective model.
• model of nuclear tunneling.

49
If the stable nuclei are plotted with neutron
number vs. proton number, the curve formed by the
stable nuclei does not follow the line N Z.
This is predicted by examining how the binding
energy is influenced by?
• the volume of the nucleus.
• the size of the nuclear surface.
• the Coulomb repulsion.
• the proton-neutron mass difference.

50
The binding energy of a nucleus is equal to?
• the energy needed to remove one of the nucleons.
• the average energy with which any nucleon is
bound in the nucleus.
• the energy needed to separate all the nucleons
from each other.
• the mass of the nucleus times c2.

51
The gram molecular mass for chlorine is not a
multiple of the mass of hydrogen but is about
35.5 times the mass of hydrogen. This is
primarily because?
• the proton and neutron have different masses.
• there are several isotopes of chlorine.
• of the binding energy of the chlorine nucleus.
• the chlorine nucleus has 35.5 nucleons.

52
The mass of 238U is not quite an integer multiple
of -H. This is primarily because?
• the proton and neutron have different masses.
• there are several isotopes of uranium.
• of the binding energy of uranium.

53
The neutron is radioactive and can beta decay to
form a proton. This can occur primarily because?
• the proton has less mass than a neutron.
• there are several hydrogen isotopes.
• of the binding energy of hydrogen.
• the neutron is neutral.

54
For every stable nucleus except hydrogen, if the
number of nucleons is doubled, the quantity that
will change least is the?
• mass.
• charge.
• volume.
• density.

55
What particle is emitted when P-32 decays to
S-32? (atomic numbers of P and S are,
respectively, 15 and 16)
• alpha
• beta
• positron
• gamma quantum

56
What particle is emitted when Pu-240 decays to
U-236? (atomic numbers of Pu and U are,
respectively, 94 and 92)
• alpha
• beta
• positron
• gamma quantum

57
The original nucleus and the final nucleus will
be isotopes for which decay scheme of the
original nucleus?
• alpha decay followed by two beta decays
• two gamma decays
• a beta decay followed by an alpha decay
• a beta decay followed by neutron emission

58
The mass of 12C is 12 u where 1 u 1.660559 x
10-27 kg. This mass is equal to?
• the mass of the 12C nucleus.
• the mass of the 12C nucleus plus 6 electrons.
• the mass of the 12C nucleus plus 12 electrons.
• the mass of 6 protons and 6 neutrons.

59
A proton is captured by an oxygen-16 atom which
in turn emits a deuteron. What is the element and
mass number of the product isotope?
• nitrogen-15
• oxygen-17
• oxygen-15
• fluorine-15