Question 1

Heavy nuclei are unstable because

Accepted Answer

A) each nucleon is a separate particle that is not acted on by the nuclear force. 
B) there are not enough protons present relative to the number of neutrons for the electrical force to be strong enough. 
C) the nuclear force dominates the Coulomb repulsive force at distances less than 2 fm,but falls off rapidly at greater distances. 
D) nuclei are stable only when the number of neutrons equals the number of protons. 
E) nuclei are stable only when the number of protons exceeds the number of neutrons. 
A) each nucleon is a separate particle that is not acted on by the nuclear force. 
B) there are not enough protons present relative to the number of neutrons for the electrical force to be strong enough. 
C) the nuclear force dominates the Coulomb repulsive force at distances less than 2 fm,but falls off rapidly at greater distances. 
D) nuclei are stable only when the number of neutrons equals the number of protons. 
E) nuclei are stable only when the number of protons exceeds the number of neutrons.

Question 2

What is the disintegration energy (in MeV)associated with this spontaneous decay?  
MNd = 143.910 083 u
MCe = 139.905 434 u
MHe = 4.002 603 u
1 u = 1.66 × 10−27 kg

Accepted Answer

A) 1.54 
B) 2.37 
C) 1.90 
D) 4.13 
E) 8.21 
A) 1.54 
B) 2.37 
C) 1.90 
D) 4.13 
E) 8.21

Question 3

It is often possible to use atomic masses when calculating the binding energy of a nucleus.This is not true for calculating the Q value for the e+ decay process since

Accepted Answer

A) the electron masses do not cancel. 
B) a positron is an antiparticle. 
C) the electron masses cancel. 
D) the mass of a positron cannot be neglected when compared to the mass of a nucleus. 
E) none of the above. 
A) the electron masses do not cancel. 
B) a positron is an antiparticle. 
C) the electron masses cancel. 
D) the mass of a positron cannot be neglected when compared to the mass of a nucleus. 
E) none of the above.

Question 4

How can a nucleus be described by particular values of A,Z and N when the mass of the nucleus is not equal to Zmp + Nmn,where mp and mn are the masses of free protons and neutrons?

Accepted Answer

A) A,Z and N have no intrinsic meaning. 
B) A,Z and N describe the number of particles of given types,but mass has no meaning when part of the mass is elsewhere in the universe. 
C) A,Z and N describe the number of particles an ideal rather than a real nucleus would have. 
D) A,Z and N describe the number of particles of given types in the nucleus,but not their masses in a bound state. 
E) A,Z and N describe the number of particles of given types in the nucleus since the missing mass consists of electrons that are also present in the nucleus. 
A) A,Z and N have no intrinsic meaning. 
B) A,Z and N describe the number of particles of given types,but mass has no meaning when part of the mass is elsewhere in the universe. 
C) A,Z and N describe the number of particles an ideal rather than a real nucleus would have. 
D) A,Z and N describe the number of particles of given types in the nucleus,but not their masses in a bound state. 
E) A,Z and N describe the number of particles of given types in the nucleus since the missing mass consists of electrons that are also present in the nucleus.

Question 5

The chart below shows part of the radioactive series beginning with the isotope  
)The isotope marked with an X is

Accepted Answer

A)    . 
B)    . 
C)    . 
D)    . 
E)    . 
A)    . 
B)    . 
C)    . 
D)    . 
E)    .

Question 6

The radius of a nucleus of  
(in fm)is

Accepted Answer

A) 15.4 
B) 5.5 
C) 12.8 
D) 6.6 
E) 4.9 
A) 15.4 
B) 5.5 
C) 12.8 
D) 6.6 
E) 4.9

Question 7

The half-life of 131I is 8 days.On a certain day,the activity of an 131I sample is 6.4 mCi.What is its activity 40 days later?

Accepted Answer

Question 8

In nuclear magnetic resonance,nuclei absorb energy when flipping between nuclear

Accepted Answer

A) mass states. 
B) spin states. 
C) charge states. 
D) decay states. 
E) isotope states. 
A) mass states. 
B) spin states. 
C) charge states. 
D) decay states. 
E) isotope states.

Question 9

The radius of an approximately spherical nucleus is given by r =

Accepted Answer

A) r0Z3. 
B) r0Z1/3. 
C) r0A3. 
D) r0A1/3. 
E) r0(A − Z)1/3. 
A) r0Z3. 
B) r0Z1/3. 
C) r0A3. 
D) r0A1/3. 
E) r0(A − Z)1/3.

Question 10

According to the shell model,binding energy per nucleon is greater when N or Z is equal to one of the numbers below except for

Accepted Answer

A) 2. 
B) 8. 
C) 13. 
D) 20. 
E) 28. 
A) 2. 
B) 8. 
C) 13. 
D) 20. 
E) 28.

Question 11

Which of the effects listed below is not a major effect influencing the binding energy of the nucleus in the liquid-drop model?

Accepted Answer

A) The volume effect: the binding energy per nucleon is approximately constant when A > 50. 
B) The surface effect: nucleons in the surface have fewer neighbors. 
C) The quantum number effect: all nucleons in the nucleus have the same set of quantum numbers. 
D) The Coulomb repulsion effect: protons repel protons. 
E) The symmetry effect: stable nuclei tend to have N ≈ Z. 
A) The volume effect: the binding energy per nucleon is approximately constant when A > 50. 
B) The surface effect: nucleons in the surface have fewer neighbors. 
C) The quantum number effect: all nucleons in the nucleus have the same set of quantum numbers. 
D) The Coulomb repulsion effect: protons repel protons. 
E) The symmetry effect: stable nuclei tend to have N ≈ Z.

Question 12

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the initial decay rate,at t = 0 (in decays/s)?

Accepted Answer

A) 1.09 × 1014 
B) 1.8 × 10−9 
C) 5.6 × 108 
D) 3.6 × 1018 
E) 3.6 × 1017 
A) 1.09 × 1014 
B) 1.8 × 10−9 
C) 5.6 × 108 
D) 3.6 × 1018 
E) 3.6 × 1017

Question 13

How many radioactive atoms are present in a sample that has an activity of 0.5 μCi and a half-life of 10 years? (1 curie = 3.7 × 1010 decays/s)

Accepted Answer

A) 9.5 × 1012 atoms 
B) 8.4 × 1012 atoms 
C) 7.3 × 1012 atoms 
D) 6.5 × 1012 atoms 
E) 2.7 × 105 atoms 
A) 9.5 × 1012 atoms 
B) 8.4 × 1012 atoms 
C) 7.3 × 1012 atoms 
D) 6.5 × 1012 atoms 
E) 2.7 × 105 atoms

Question 14

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.How much tritium will be left after 30 years?

Accepted Answer

A) 0.20 kg 
B) 1.8 kg 
C) 0.18 kg 
D) 1.7 kg 
E) 4.1 kg 
A) 0.20 kg 
B) 1.8 kg 
C) 0.18 kg 
D) 1.7 kg 
E) 4.1 kg

Question 15

The ratio of the density of a neutron (r = r0A1/3)to the density of a classical electron (re = ke2/mec2 = 2.8 × 10−15 m)is

Accepted Answer

A) 4.3 × 102 
B) 2.3 × 104 
C) 1.4 × 102 
D) 6.9 × 10−3 
E) 4.3 × 103 
A) 4.3 × 102 
B) 2.3 × 104 
C) 1.4 × 102 
D) 6.9 × 10−3 
E) 4.3 × 103

Question 16

One of the naturally occurring radioactive series begins with  
)Which of the following isotopes is the stable isotope at the end of this series?

Accepted Answer

A)    
B)    
C)    
D)    
E) None of the above choices can be correct. 
A)    
B)    
C)    
D)    
E) None of the above choices can be correct.

Question 17

The Q value for the following reaction,  
,is (in MeV)
M(alpha)= 4.002 603 u
M(Be)= 9.012 182 u
m(n.= 1.008 665 u
M(C)= 12.000 00 u
1 u = 1.66 × 10−27 kg

Accepted Answer

A) 8.4 
B) 6.2 
C) 7.3 
D) 5.7 
E) 3.5 
A) 8.4 
B) 6.2 
C) 7.3 
D) 5.7 
E) 3.5

Question 18

An alpha particle is emitted from a radioactive source with an energy of 5 MeV.How fast is it moving (in m/s)? (m = 4.002 603 u,1 u = 1.66 × 10−27 kg. )

Accepted Answer

A) 2.4 × 107 
B) 1.6 × 107 
C) 3.7 × 107 
D) 4.6 × 107 
E) 2.1 × 107 
A) 2.4 × 107 
B) 1.6 × 107 
C) 3.7 × 107 
D) 4.6 × 107 
E) 2.1 × 107

Question 19

Linus claims that the added gravitational force of neutrons holds the particles in a nucleus together.Linnea says that they stick together because they lose their electric charge when they form a nucleus.Which one,if either,is correct,and why?

Accepted Answer

A) Linus,because more particles exert gravitational forces on one another than exert electromagnetic forces. 
B) Linus,because the numerical magnitude of G/ke is 7.42 × 10−21. 
C) Linnea,because the numerical magnitude of G/ke is 7.42 × 10−21. 
D) Both,because electric charge is lost and then gravity holds the nucleus together. 
E) Neither,because gravity is not lost,and the numerical magnitude of ke/G is 1.35 × 1020. 
A) Linus,because more particles exert gravitational forces on one another than exert electromagnetic forces. 
B) Linus,because the numerical magnitude of G/ke is 7.42 × 10−21. 
C) Linnea,because the numerical magnitude of G/ke is 7.42 × 10−21. 
D) Both,because electric charge is lost and then gravity holds the nucleus together. 
E) Neither,because gravity is not lost,and the numerical magnitude of ke/G is 1.35 × 1020.

Question 20

It is often possible to use the atomic masses when calculating the binding energy of a nucleus.The reason for this is

Accepted Answer

A) the electron masses do not cancel. 
B) the electron masses cancel. 
C) tables of nuclear masses are usually not available. 
D) the mass of the electron can usually be neglected when compared to the mass of the neutron. 
E) the atomic masses are the same as the nuclear masses. 
A) the electron masses do not cancel. 
B) the electron masses cancel. 
C) tables of nuclear masses are usually not available. 
D) the mass of the electron can usually be neglected when compared to the mass of the neutron. 
E) the atomic masses are the same as the nuclear masses.

Exam 44: Nuclear Structure

Heavy nuclei are unstable because

What is the disintegration energy (in MeV)associated with this spontaneous decay? MNd = 143.910 083 u MCe = 139.905 434 u MHe = 4.002 603 u 1 u = 1.66 × 10−27 kg

It is often possible to use atomic masses when calculating the binding energy of a nucleus.This is not true for calculating the Q value for the e+ decay process since

How can a nucleus be described by particular values of A,Z and N when the mass of the nucleus is not equal to Zmp + Nmn,where mp and mn are the masses of free protons and neutrons?

The chart below shows part of the radioactive series beginning with the isotope )The isotope marked with an X is

The radius of a nucleus of (in fm)is

The half-life of 131I is 8 days.On a certain day,the activity of an 131I sample is 6.4 mCi.What is its activity 40 days later?

In nuclear magnetic resonance,nuclei absorb energy when flipping between nuclear

The radius of an approximately spherical nucleus is given by r =

According to the shell model,binding energy per nucleon is greater when N or Z is equal to one of the numbers below except for

Which of the effects listed below is not a major effect influencing the binding energy of the nucleus in the liquid-drop model?

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the initial decay rate,at t = 0 (in decays/s)?

How many radioactive atoms are present in a sample that has an activity of 0.5 μCi and a half-life of 10 years? (1 curie = 3.7 × 1010 decays/s)

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.How much tritium will be left after 30 years?

The ratio of the density of a neutron (r = r0A1/3)to the density of a classical electron (re = ke2/mec2 = 2.8 × 10−15 m)is

One of the naturally occurring radioactive series begins with )Which of the following isotopes is the stable isotope at the end of this series?

The Q value for the following reaction, ,is (in MeV) M(alpha)= 4.002 603 u M(Be)= 9.012 182 u m(n.= 1.008 665 u M(C)= 12.000 00 u 1 u = 1.66 × 10−27 kg

An alpha particle is emitted from a radioactive source with an energy of 5 MeV.How fast is it moving (in m/s)? (m = 4.002 603 u,1 u = 1.66 × 10−27 kg. )

Linus claims that the added gravitational force of neutrons holds the particles in a nucleus together.Linnea says that they stick together because they lose their electric charge when they form a nucleus.Which one,if either,is correct,and why?

It is often possible to use the atomic masses when calculating the binding energy of a nucleus.The reason for this is

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What is the disintegration energy (in MeV)associated with this spontaneous decay? M_Nd = 143.910 083 u M_Ce = 139.905 434 u M_He = 4.002 603 u 1 u = 1.66 × 10−²⁷ kg

It is often possible to use atomic masses when calculating the binding energy of a nucleus.This is not true for calculating the Q value for the e⁺ decay process since

How can a nucleus be described by particular values of A,Z and N when the mass of the nucleus is not equal to Zm_p + Nm_n,where m_p and m_n are the masses of free protons and neutrons?

The half-life of ¹³¹I is 8 days.On a certain day,the activity of an ¹³¹I sample is 6.4 mCi.What is its activity 40 days later?

How many radioactive atoms are present in a sample that has an activity of 0.5 μCi and a half-life of 10 years? (1 curie = 3.7 × 10¹⁰ decays/s)

The ratio of the density of a neutron (r = r₀A^1/3)to the density of a classical electron (r_e = ke²/m_ec² = 2.8 × 10−¹⁵ m)is

The Q value for the following reaction, ,is (in MeV) M(alpha)= 4.002 603 u M(Be)= 9.012 182 u m(n.= 1.008 665 u M(C)= 12.000 00 u 1 u = 1.66 × 10−²⁷ kg

An alpha particle is emitted from a radioactive source with an energy of 5 MeV.How fast is it moving (in m/s)? (m = 4.002 603 u,1 u = 1.66 × 10−²⁷ kg. )