Deck 40: Nuclear Physics

Question 1

A certain radioactive isotope decays to one sixteenth of its original amount in 4.0 hours.What is its half-life?

A)1.0 hours
B)2.5 hours
C)2.0 hours
D)1.4 hours

Answer 1

1.0 hours

Question 2

A radioactive atom undergoes $\beta$ ^- decay by emitting an electron and an anti-electron neutrino.When this occurs,what happens to the number of neutrons in the atom?

A)increases.
B)decreases.
C)remains constant.
D)One can't determine what happens to the number of neutrons using only the information given.

Answer 2

decreases.

Question 3

A certain radioactive isotope decays to one fourth of its original amount in 4.0 hours.How long would it take for 20% of it to decay?

A)0.40 hours
B)0.56 hours
C)0.64 hours
D)0.85 hours

Answer 3

0.64 hours

Question 4

A radioactive atom undergoes $\beta$ ^- decay by emitting an electron and an anti-electron neutrino.When this occurs,what happens to the number of protons in the atom?

A)increases.
B)decreases.
C)remains constant.
D)One can't determine what happens to the number of protons using only the information given.

Question 5

A certain radioactive isotope decays to one fourth of its original amount in 4.0 hours.What is its half life?

A)1.4 hours
B)2.0 hours
C)2.5 hours
D)3.4 hours

Question 6

A drug containing with an activity of 2.00 $\mu$ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 $\mu$ Ci.What is the half-life of ?

A)6.05 hr
B)8.74 hr
C)12.6 hr
D)7.45 hr
E)6.91 hr

Question 7

An archeologist discovers the bones of a person believed to have been dead for 600 years.Using carbon dating,they wish to confirm the time of the person's demise.The rate of change of is 0.270 Bq/g of carbon for the bones of a person who had just died.If the archeologist is correct about the person's time of death,what rate of change of should they find when they carbon date the bones? The half life of is 5.73 x 10³ y.

A)0.245 Bq/g
B)0.267 Bq/g
C)0.251 Bq/g
D)0.238 Bq/g
E)0.259 Bq/g

Question 8

The rate of change of is 0.270 Bq per gram of carbon for the bones of a person who had just died.What is the decay constant? The half life of is 5.73 *10³ y^-1.

A)1.21 x 10^-4 y
B)2.31 x 10^-4 y
C)4.69 x 10^-4 y
D)5.25 x 10^-4 y
E)6.34 x 10^-4 y

Question 9

A radioactive atom emits an alpha particle.When this occurs,what happens to the mass number of the atom?

A)It increases.
B)It decreases.
C)It remains constant.
D)One can't determine what happens to the atomic number using only the information given.

Question 10

A drug containing ( t _1/2 = 6.05 h)with an activity of 2.00 $\mu$ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).What activity should the drug have at the preparation time (7:00 am)?

A)0.25 $\mu$ Ci
B)1.34 $\mu$ Ci
C)2.87 $\mu$ Ci
D)3.16 $\mu$ Ci
E)4.47 $\mu$ Ci

Question 11

A certain radioactive isotope decays to one sixteenth of its original amount in 4.0 hours.What is its mean lifetime?

A)1.4 hours
B)2.0 hours
C)2.5 hours
D)3.4 hours

Question 12

Which elements have the most stable nuclei because they have the greatest binding energy per nucleon?

A)hydrogen and helium
B)krypton and barium
C)iron and nickel
D)uranium and plutonium

Question 13

An archeologist discovers the bones of a person who appeared to have been dead a very long time.Using carbon dating,they determine that the rate of change of the is 0.259 Bq per gram of carbon for the bones.The rate of change of is 0.270 Bq per gram of carbon for the bones of a person who had just died.How old are the bones? The half life of is 5.73 x 10³ y.

A)120 years
B)259 years
C)343 years
D)568 years
E)754 years

Question 14

A drug containing with an activity of 2.00 $\mu$ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 $\mu$ Ci.What is the decay constant of ?

A)0.165 hr^-1
B)0.114 hr^-1
C)0.0793 hr^-1
D)0.204 hr^-1
E)0.0961 hr^-1

Question 15

A certain radioactive isotope has a half-life of 4.0 hours.How much time does it take for the amount of the isotope to decrease to one-eighth of its initial amount?

A)12 hours
B)8.0 hours
C)64 hours
D)16 hours

Question 16

A nuclear fission power plant produces about 2.50 GW of electrical power.Assume that the plant has an overall efficiency of 40.0% and that each fission produces 200.0 MeV of energy.Calculate the mass of ²³⁵U consumed each day.

A)1.05 kg
B)2.63 kg
C)4.89 kg
D)6.58 kg
E)7.11 kg

Question 17

The nucleus of a radioactive atom captures one of the atom's innermost electrons.When this occurs,what happens to the mass number of the atom?

A)It increases.
B)It decreases.
C)It remains constant.
D)One can't determine what happens to the atomic number using only the information given.

Question 18

A drug containing with an activity of 2.00 $\mu$ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 $\mu$ Ci.What is the mean lifetime of ?

A)6.05 hr
B)8.74 hr
C)12.6 hr
D)7.45 hr
E)6.91 hr

Question 19

A drug containing ( = 6.05 h)is to be injected into a patient at 10:00 am.You are to prepare the sample 3.00 hours before the injection (at 7:00 am)with an activity of 3.53 $\mu$ Ci at the preparation time (7:00 am).What will be the activity of the sample at the time of the injection?

A)1.50 $\mu$ Ci
B)2.00 $\mu$ Ci
C)2.50 $\mu$ Ci
D)3.00 $\mu$ Ci
E)3.50 $\mu$ Ci

Question 20

Atoms consist of protons,neutrons,and electrons.Which determines an element of the periodic table?

A)the number of protons only
B)the number of neutrons only
C)the number of protons and neutrons
D)the number of protons,neutrons,and electrons

Question 21

Consider the following fusion reaction .The mass of is 3.016029 u,the mass of is 4.002602 u,and the mass of is 7.0169298 u.Assuming that the Be atom is at rest after the reaction,calculate the minimum possible energy of the photon g that is released in this reaction.

A)0.5 MeV
B)1 MeV
C)2 MeV
D)3 MeV
E)5 MeV

Question 22

A nuclear fission power plant consumes 7.11 kg of ²³⁵U each day to produce electrical power.Assume that the plant has an overall efficiency of 40.0% and that each fission produces 200.0 MeV of energy.Calculate the power output of the nuclear fission power plant.

A)2.90 GW
B)3.10 GW
C)2.70 GW
D)2.50 GW
E)2.30 GW

Question 23

The Sun has a mass of 1.99 * 10³⁰ kg and radiates energy at a rate of 3.85 *10²⁶ W.What is the change in mass of the Sun during one day?

A)1.6 * 10¹² kg
B)2.2 * 10¹³ kg
C)8.7 * 10¹³ kg
D)3.7 * 10¹⁴ kg
E)1.1 * 10²³ kg

Question 24

Calculate the binding energy per nucleon for ,which consists of 92 protons,92 electrons,and 146 neutrons with a total mass of 238.0507826 u.

A)9.03 * 10^-11 J
B)8.52 * 10^-11 J
C)2.65 * 10^-12 J
D)1.21 *10^-12 J
E)2.90 * 10^-12 J

Question 25

Assuming a neutron star is as dense as an atomic nucleus and there are 7.1 * 10⁵⁶ nucleons (almost entirely neutrons),estimate the diameter of this neutron star.

A)15 km
B)25 km
C)20 km
D)10 km
E)5 km

Question 26

Assuming that a neutron star is as dense as an atomic nucleus,estimate the mass of a neutron star having a diameter of 10 km.

A)1.5 * 10²⁹ kg
B)1.1 * 10²⁹ kg
C)3.2 * 10²⁹ kg
D)2.1 * 10²⁹ kg
E)1.8 * 10²⁹ kg

Question 27

Calculate the binding energy of ⁷Li.(The mass of ⁷Li is 7.016004 u.)

A)12.34 MeV
B)23.45 MeV
C)39.25 MeV
D)54.32 MeV
E)64.35 MeV

Question 28

What is the decay constant for ¹⁴C? Carbon 14 has a half-life of 5730 years?

A)1.2 * 10^-4 s^-1
B)5.3 * 10^-5 s^-1
C)1.7 * 10^-12 s^-1
D)3.8 * 10^-12 s^-1
E)5.5 * 10^-12 s^-1

Question 29

In 1991 a frozen body of an "Iceman" was found in the Italian Alps.The fraction of compared to found in the body's bones,hair,and leather clothing was 6.94 * 10^-13.The half-life of is 5,730 years and the ratio of to in living organisms is 1 to 7.41 *10¹¹.When did the Iceman die?

A)2500 years ago
B)3800 years ago
C)5500 years ago
D)7600 years ago
E)11,000 years ago

Question 30

Consider a hypothetical fission process where a nucleus splits into two identical nuclei without producing any other particles or radiation.The mass of is 119.904040 u,and the mass of is 59.934078 u.At the moment when the two Fe nuclei form,but before they start moving away due to Coulomb repulsion,how far apart are the two Fe nuclei?

A)3 *10^-14 m
B)7 * 10^-14 m
C)4 * 10^-13 m
D)6 * 10^-10 m
E)2 * 10^-7 m

Question 31

The fusion reaction: releases 23.85 MeV of energy.World power consumption is about 10¹³ W and 0.0300% of ocean water contains deuterium, .If the deuterium in the ocean water were fused by controlled fusion with 100% efficiency,how much water would be needed every second to cover world's power consumption?

A)0.159 kg
B)2.32 kg
C)58.3 kg
D)522 kg
E)9470 kg

Question 32

If protons decay with a half-life of 10³⁰ years,how long will it take for 1% of the protons in the universe to decay?

A)6.3 * 10²⁷ yr
B)1.0 * 10²⁸ yr
C)1.5 * 10²⁸ yr
D)9.9 * 10³¹ yr
E)1.1 * 10³² yr

Question 33

A Geiger counter initially records 9876 counts per second.After 45 minutes it records 1234 counts/s.Ignore any uncertainty in the counts and find the half-life of the material.

A)900 s
B)950 s
C)1300 s
D)1350 s
E)2072 s

Question 34

if the mass of a star changes at a rate of 8.7 * 10¹³ kg/day,at what rate does the star radiate energy?

A)2.32 * 10²⁶ W
B)3.85 * 10²⁶ W
C)1.12 * 10²⁶ W
D)8.12 * 10²⁵ W
E)9.06 * 10²⁵ W

Question 35

Element X decays to element Y via beta decay with a half-life of 0.77 s.Initially there is a sample of pure X and after 2.31 s there are 7 g of Y.What was the mass of the original sample?

A)1 g
B)7 g
C)8 g
D)14 g
E)56 g

Question 36

Which isotope of carbon is the most stable?

A)
B)
C)
D)
E)

Question 37

Assuming that a neutron star is as dense as an atomic nucleus,estimate the number of nucleons in a 10 km diameter star.

A)3.2* 10⁵³
B)4.5 * 10⁵⁴
C)8.9*10⁵⁵
D)7.1 * 10⁵⁶
E)2.1 *10⁵⁷

Question 38

Calculate the binding energy for ,which consists of 92 protons,92 electrons,and 146 neutrons with a total mass of 238.0507826 u.

A)2.65 *10^-10 J
B)2.45 * 10^-10 J
C)2.90 * 10^-10 J
D)1.03 * 10^-12 J
E)2.65 * 10^-13 J

Question 39

A nuclear fission power plant produces about 2.50 GW of electrical power.Assume that the plant has an overall efficiency of 40.0% and that each fission produces 200.0 MeV of energy.Calculate the number of ²³⁵U fissions required each day.

A)6.75 * 10²⁴
B)3.12 * 10²⁵
C)2.41 * 10²⁵
D)2.89 * 10²⁵
E)1.69 * 10²⁵

Question 40

A nuclear fission power plant produces about 2.00 GW of electrical power.Assume that that each fission produces 200.0 MeV of energy and that the mass of ²³⁵U consumed each day is 5.50 kg.The overall efficiency of the plant is

A)32.4%.
B)38.3%.
C)41.5%.
D)46.2%.
E)51.7%.

Question 41

A radioactive isotope has a lifetime of 6.30 min.If you begin with a sample of 2.50 moles of this isotope,how many atoms have you left after one hour?

A)1.10 * 10²⁰
B)4.5 * 10¹⁴
C)2.05 * 10²¹
D)None are correct.

Question 42

What is the total energy released in the following decay?

A)5 MeV
B)2 MeV
C)0.8 MeV
D)0.2 MeV

Question 43

Assuming that 200 MeV of energy is released per fission,calculate the total energy released in the fission of 1 g of ²³⁵U.

A)2.28 * 10⁴ kW h.
B)4.98 * 10⁴ kW h.
C)2.28 * 10⁵ kW h.
D)1.49 * 10⁶ kW h.

Question 44

If 10³⁰ atoms of a radioactive sample remain after 10 half-lives,how many atoms remain after 20 half-lives?

A)10²⁹
B)10²⁷
C)10²⁶
D)10²⁸

Question 45

How large is the electrostatic repulsion between two protons a distance d = 6.7 fm apart in a nucleus?

A)7.5 N
B)75.5 N
C)48.4 N
D)8.95 N
E)5.13 N

Question 46

A certain radioactive isotope has a lifetime of 343.6 s.Suppose you have a beam made of radioactive ions of this isotope travelling at 5.21 * 10⁷ m/s in the laboratory,circulating in a cyclotron.If you begin with a sample of 2.50 micro-moles of this isotope,how many atoms have you left after one hour?

A)4.97 * 10¹³
B)4.23 * 10¹³
C)3.61 * 10¹³
D)None are correct.

Question 47

¹³¹I,which has a half- life time of 8 days,is used in nuclear medicine to monitor the hormone production in the thyroid in a patient.A sample of ¹³¹I containing 5 * 10¹⁰ atoms is produced in a nuclear reactor.Due to the short half- life time,the sample emits less radiation with time.However,it is usable as long as there are at least 1.25 * 10^{10 131}I atoms present.What is the maximum time before the sample is no longer usable?

A)16 days
B)12 days
C)8 days
D)6 days

Question 48

What is the binding energy per nucleon of ⁵⁶Fe? The atomic mass of ⁵⁶Fe is 55.9349 u,the mass of a proton = 1.0078 u,the mass of a neutron = 1.0087 u,the atomic number Z = 26 and the atomic mass A = 56.

A)9.01 MeV
B)8.79 MeV
C)7.95 MeV
D)7.22 MeV

Question 49

What is the binding energy of ⁵⁶Fe? The atomic mass of ⁵⁶Fe is 55.9349 u,the mass of a proton = 1.0078 u,the mass of a neutron = 1.0087 u,the atomic number Z = 26 and the atomic mass A = 56.

A)231 MeV
B)350 MeV
C)492 MeV
D)567 MeV

Question 50

If you begin with a sample of 2.50 moles of a radioactive isotope and there are 2.05 * 10²¹ atoms left after one hour,what is the half-life of this isotope?

A)9.1 minutes
B)6.3 minutes
C)13 minutes
D)7.5 minutes

Question 51

What is the surface area,approximately,of a Lead-208 nucleus (Z = 82)?

A)550 fm²
B)140 fm²
C)440 fm²
D)74 fm²
E)120 fm²

Question 52

The half-life of a sample of 10¹¹ atoms that decay by alpha emission is 10 minutes.How many alpha particles are emitted between the time interval 100 min and 200 min?

A)9.8 * 10⁷
B)9.8 * 10⁴
C)2.0 * 10⁶
D)1.0 * 10⁷

Question 53

If you begin with a sample of 2.50 moles of a radioactive isotope and there are 2.05 * 10²¹ atoms left after one hour,what is the mean lifetime of this isotope?

A)8.4 minutes
B)7.5 minutes
C)6.3 minutes
D)9.1 minutes

Question 54

3.25 mole of a radioactive isotope with a half-life of 18.2 hours sits on a countertop for 2.7 days exactly.How much of the isotope is left?

A)0.14 mole
B)0.28 mole
C)1.34 mole
D)2.47 mole
E)3.25 mole

Question 55

In neutron stars,which are roughly 90% neutrons and supported almost entirely by nuclear forces,which of the following binding energy terms becomes relatively dominant compared to ordinary nuclei?

A)the coulomb term
B)the asymmetry term
C)the pairing term
D)All are correct.
E)None are correct.

Question 56

Which of the following is true about strong force?

A)is only attractive
B)does not act on electrons
C)only acts over a few fm
D)All are correct.

Question 57

If the Fermi energy of a neutron inside a nucleus is 38 MeV,estimate the maximum speed with which it moves around inside the nucleus.

A)90% of speed of light
B)10% of speed of light
C)0.1% of speed of light
D)30% of speed of light

Question 58

If the Fermi energy of a neutron inside a nucleus is 38 MeV,what is the Fermi momentum?

A)38 MeV/c
B)270 MeV/c
C)370 MeV/c
D)154 MeV/c

Question 59

A radioactive isotope has a lifetime of 6.30 min.If you begin with a sample of this isotope and there are 2.05 * 10²¹ atoms left after one hour,how many moles were in your initial sample?

A)2.50
B)46.6
C)17.2
D)98.5

Question 60

Which of the following would you expect to decay via b⁺ decay?

A)¹²C
B)¹³²Sn
C)⁵⁶Fe
D)⁷⁴Kr
E)¹⁷N

Question 61

A radioactive material has a half life of 20 seconds.If the initial amount of material is G grams,how much will be left at the end of one minute?

A)G/3
B)G/4
C)G/6
D)G/8
E)G/16

Question 62

When ²¹⁵₈₃Bi decays to ²¹⁵₈₄Po,what particle is released?

A)proton
B)neutron
C)positron
D)electron
E)alpha

Question 63

What particle has 9 protons,10 neutrons,and 11 electrons?

A)¹⁰F^-2
B)¹⁹F^-2
C)⁹Ne^-2
D)¹⁹Ne^-2
E)⁹K^-2

Question 64

A Geiger counter placed next to a radioactive sample produces 200 counts per minute.One hour later,the Geiger counter reads 180 counts per minute.What is the half-life of the radioactive sample?

A)1.1 hours
B)6.6 hours
C)9.0 hours
D)9.5 hours
E)10 hours

Question 65

Sirius,the brightest star in the night sky coverts 3.216 * 10¹⁸ kg of its mass to energy every year.What is the luminosity (power radiated)of Sirius?

A)3.91 * 10²⁶ W
B)1.09 * 10²⁷ W
C)1.33 * 10²⁸ W
D)5.23 * 10²⁷ W
E)9.18 * 10²⁷ W

Question 66

In a $\beta$ ^- decay process, .If A has mass 14.0032235 u and B has mass 14.0031592 u,what is the maximum energy of the emitted electron?

A)0.26 keV
B)12.4 keV
C)59.9 keV
D)231keV
E)4186 keV

Question 67

When carbon-14 undergoes a beta decay,an isotope of what element is produced?

A)beryllium
B)boron
C)carbon
D)nitrogen
E)oxygen

Question 68

U-238 has a half-life of 4.5 billion years and a present day abundance of 99.3%.U-235 has a half-life of 0.7 billion years and a present day abundance of 0.7%.Assuming a steady rate of decay,how long ago did these two isotopes have the same abundance?

A)4.1 billion years ago
B)5.2 billion years ago
C)5.9 billion years ago
D)8.4 billion years ago
E)9.9 billion years ago

Question 69

The volume of a nucleus is proportional to

A)the atomic number Z.
B)the atomic mass number
C)the neutron number N.
D)the number of electrons.

Question 70

A muon has a mean lifetime of only 2.200 µs in its own rest frame.If it moves with a speed of v = 0.9994 c in a certain reference frame,what is its mean lifetime in that frame?

A)0.042 µs
B)2.2 µs
C)9.99 µs
D)63.5 µs
E)4200 µs

Question 71

An iron isotope of iron,⁵⁶Fe,has a binding energy per nucleon of 8.791 MeV.What is its mass? (The mass of an hydrogen atom is 1.007825 u,the mass of a neutron is 1.008665 u,and the atomic mass unit is 1 u = 931.5 MeV.The number of protons in the iron nucleus is 26.)

A)26.20345 u
B)30.23475 u
C)55.93494 u
D)56.46340 u
E)56.99186 u

Question 72

A tree is chopped down and burned to produce ash.The carbon isotopes in the ash are found to have a ratio for ¹⁴C to ¹²C of 1.3 * 10^-12.Experimental tests on the ¹⁴C atoms reveal that ¹⁴C is a beta emitter with a half-life of 5730 years.At an archeological excavation,a skeleton is found next to a campfire with some wood ash.If 100 g of carbon from the ash in the campfire emits betas at a rate of 40 per hour,how old is the campfire?

A)44,000 years
B)64,000 years
C)98,000 years
D)230,000 years
E)4,500,000 years

Question 73

Betelgeuse has a luminosity (power radiated)135,000 times that of the Sun,which emits energy at the rate of 3.906 * 10²⁶ W.How much of its mass is being converted to energy in each year?

A)1.85 * 10²² kg
B)7.70 * 10²⁰ kg
C)1.37 * 10¹⁷ kg
D)5.85 * 10¹⁴ kg
E)5.06 * 10¹⁹ kg

Question 74

When ²¹⁰₈₃Bi decays its half life is 5.0 seconds.What is the activity in Bq (disintegrations per second)of one mole?

A)6.02 * 10²³/5
B)0.69 * 6.02 * 10²³/5
C)5 * 6.02 * 10²³
D)6.02 * 10²³/5 * 0.69
E)5 * 6.02 * 10²³/0.69

Question 75

The half-life of Co-57 is 271.8 days;calculate the decay constant.

A)11.2 * 10^-8 s^-1
B)16.0 * 10^-4 s^-1
C)2.95 * 10⁸ s^-1
D)3.0 * 10^-8 s^-1
E)6.3 * 10⁶ s^-1

Question 76

Sirius,the brightest star in the night sky coverts 3.216 * 10¹⁸ kg of its mass to energy every year.How does the luminosity (power radiated)of Sirius compare to that of the sun? L_sun = 3.906 * 10²⁶ W

A)17.6L_sun
B)23.5L_sun
C)3.56L_sun
D)36.7L_sun
E)42.0L_sun

Question 77

If Carbon-14,a beta emitter with a half-life of 5730 years,makes up one out of 10¹² Carbon atoms in nature,how many decays per second are there in a 15 kg bag of charcoal (taken to be 100% carbon)?

A)1720
B)2010
C)2480
D)2890
E)None are correct.