Question 1

Radiant energy reaching the Earth from the sun is not sufficient to keep the Earth's surface temperature comfortable for life.Of the following,the most likely source of the additional thermal energy is from

Accepted Answer

A)  fusion of hydrogen nuclei in the Earth's core.
B)  fusion of high Z nuclei in the Earth's core.
C)  fission of radioactive nuclei inside the Earth.
D)  fission of radioactive nuclei in cosmic rays.
E)  deflection of radioactive nuclei in cosmic rays. C

Question 2

A pure sample of ²²⁶Ra contains 2.0 * 10¹⁴ atoms of the isotope.If the half-life of ²²⁶Ra = 1.6 * 10³ years,what is the decay rate of this sample? (1 Ci = 3.7 * 10¹⁰ decays/s)

Accepted Answer

7.4*10 ^- ⁸ Ci

Question 3

The chart below shows part of the radioactive series beginning with the isotope ${ } _ { 90 } ^ { 232 } \mathrm { Th }$ .The isotope marked with an X is

Accepted Answer

A)    88222Ra{ } _ { 88 } ^ { 222 } \mathrm { Ra }88222​Ra  .
B)    88224Ra{ } _ { 88 } ^ { 224 } \mathrm { Ra }88224​Ra  .
C)    89228Ac{ } _ { 89 } ^ { 228 } \mathrm { Ac }89228​Ac  .
D)    224Th224 \mathrm { Th }224Th  .
E)    90228Th{ } _ { 90 } ^ { 228 } \mathrm { Th }90228​Th  .  B

Question 4

Rutherford's experiment,in which he fired alpha particles of 7.7 MeV kinetic energy at a thin gold foil,showed that nuclei were very much smaller than the size of an atom because

Accepted Answer

A)  some alpha particles passed through the foil undeflected.
B)  some alpha particles were deflected backwards.
C)  some alpha particles were captured by the gold nuclei.
D)  the alpha particles could not get closer than 10 - 10 m to the gold nuclei.
E)  the alpha particles split into deuterium nuclei when they encountered the gold nuclei.

Question 5

Calculate the binding energy per nucleon (MeV/nucleon)for tritium,( ${ } _ { 1 } ^ { 3 } \mathrm { H }$ )a radioactive isotope of hydrogen. Assume:
M p = 1.007 825 u
M n = 1.008 665 u
M t = 3.016 05 u
U = 1.66 *10-27 kg

Accepted Answer

A)  2.8
B)  3.1
C)  1.0
D)  8.5
E)  2.1

Question 6

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.

Question 7

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the disintegration constant (in s - 1)?

Accepted Answer

A)  5.6 *10 - 2
B)  5.6 *108
C)  3.2 * 107
D)  1.8 *10 - 9
E)  1.6 * 106

Question 8

What value of Z (atomic number)and A (mass number)result in the following alpha decay? ${ } _ { 92 } ^ { 238 } U \rightarrow { } _ { z } ^ { A } X + \alpha$

Accepted Answer

A)  Z = 92;A = 238
B)  Z = 91;A = 238
C)  Z = 90;A = 234
D)  Z = 93;A = 238
E)  Z = 88;A = 236

Question 9

What value of Z (atomic number)and A (mass number)result in the following gamma decay? $${ } _ { 6 } ^ { 12 } \mathrm { C } \rightarrow { } _ { z } ^ { A } \mathrm { X } + \gamma$$

Accepted Answer

A)  Z = 5;A = 12
B)  Z = 4;A = 8
C)  Z = 7;A = 12
D)  Z = 6;A = 12
E)  Z = 6;A = 11

Question 10

Two nuclei which share the same mass number A always are (Hint: Eliminate any wrong answers. )

Accepted Answer

A)  stable.
B)  unstable.
C)  isotopes.
D)  isobars.
E)  radioactive.

Question 11

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

Question 12

The ratio of the radius of a classical electron (re = kee2/mec2 = 2.8 * 10 - 15 m)to the radius of a 4He nucleus (r = r0A1/3)is

Accepted Answer

A)  2.0
B)  0.68
C)  1.5
D)  0.92
E)  2.4

Question 13

In which of the following decays does the atomic mass number of the daughter nucleus differ from that of the parent nucleus?

Accepted Answer

A)    α\alphaα 
B)    β+\beta ^ { + }β+ 
C)    β−\beta ^ { - }β− 
D)    γ\gammaγ 
E)  Answers (a) ,(b) ,and (c) are correct.

Question 14

When a fast neutron collides with a hydrogen or deuterium nucleus,the most likely result is that

Accepted Answer

A)  the neutron has an appreciable gain in kinetic energy,the gain being greatest for head-on collisions.
B)  the neutron has an appreciable gain in kinetic energy,the gain being greatest for oblique collisions.
C)  the neutron has an appreciable loss in kinetic energy,the loss being greatest for head-on collisions.
D)  the neutron has an appreciable loss in kinetic energy,the loss being greatest for oblique collisions.
E)  the neutron is absorbed by the hydrogen or deuterium nucleus.

Question 15

Homer says that we can safely use nuclear power because all radioactive nuclei are gone after two half-lives.Marge says that only the decay rate is zero after two half-lives.Which one,if either,is correct,and why?

Accepted Answer

A)  Homer,because half of the nuclei disintegrate in each half-life.
B)  Marge,because the number of decays per unit time is halved in each half-life.
C)  Homer,because it's safe to handle radioactive substances after two half-lives.
D)  Both,because when all nuclei disintegrate the decay rate is also zero.
E)  Neither,because one quarter of the nuclei are left after two half-lives.

Question 16

When a nucleus at rest spontaneously splits into fragments of mass m1 and m2,the ratio of the momentum of m1 to the momentum of m2 is

Accepted Answer

A)    −m1m1+m2- \frac { m _ { 1 } } { m _ { 1 } + m _ { 2 } }−m1​+m2​m1​​  .
B)    −m2m1+m2- \frac { m _ { 2 } } { m _ { 1 } + m _ { 2 } }−m1​+m2​m2​​  .
C)  -1.
D)    +m1+m2m1+ \frac { m _ { 1 } + m _ { 2 } } { m _ { 1 } }+m1​m1​+m2​​  .
E)    +m1+m2m2+ \frac { m _ { 1 } + m _ { 2 } } { m _ { 2 } }+m2​m1​+m2​​  .

Question 17

For large mass number nuclei which are stable,the ratio of protons to neutrons is

Accepted Answer

A)  equal to 1
B)  greater than 1
C)  less than 1
D)  unrelated to the stability of nuclei
E)  almost 2 to 1

Question 18

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

The answer of The half-life of ¹³¹I is 8 days.On...

Question 19

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.

Question 20

Two nuclei may have equal Z,but different A,because they contain

Accepted Answer

A)  equal numbers of protons and neutrons.
B)  equal numbers of protons but different numbers of neutrons.
C)  different numbers of protons but equal numbers of neutrons.
D)  different numbers of protons and neutrons.
E)  electrons as well as neutrons.

Exam 30: Nuclear Physics

Radiant energy reaching the Earth from the sun is not sufficient to keep the Earth's surface temperature comfortable for life.Of the following,the most likely source of the additional thermal energy is from

A pure sample of ²²⁶Ra contains 2.0 * 10¹⁴ atoms of the isotope.If the half-life of ²²⁶Ra = 1.6 * 10³ years,what is the decay rate of this sample? (1 Ci = 3.7 * 10¹⁰ decays/s)

Rutherford's experiment,in which he fired alpha particles of 7.7 MeV kinetic energy at a thin gold foil,showed that nuclei were very much smaller than the size of an atom because

Calculate the binding energy per nucleon (MeV/nucleon) for tritium,( ${ } _ { 1 } ^ { 3 } \mathrm { H }$ ) a radioactive isotope of hydrogen. Assume: M_p = 1.007 825 u M_n = 1.008 665 u M_t = 3.016 05 u U = 1.66 *10^-²⁷ kg

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

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the disintegration constant (in s ^- ¹) ?

What value of Z (atomic number) and A (mass number) result in the following alpha decay? ${ } _ { 92 } ^ { 238 } U \rightarrow { } _ { z } ^ { A } X + \alpha$

What value of Z (atomic number) and A (mass number) result in the following gamma decay? ${ } _ { 6 } ^ { 12 } \mathrm { C } \rightarrow { } _ { z } ^ { A } \mathrm { X } + \gamma$

Two nuclei which share the same mass number A always are (Hint: Eliminate any wrong answers. )

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 radius of a classical electron (r_e = k_ee²/m_ec² = 2.8 * 10 ^- ¹⁵m) to the radius of a ⁴He nucleus (r = r₀A^1/3) is

In which of the following decays does the atomic mass number of the daughter nucleus differ from that of the parent nucleus?

When a fast neutron collides with a hydrogen or deuterium nucleus,the most likely result is that

Homer says that we can safely use nuclear power because all radioactive nuclei are gone after two half-lives.Marge says that only the decay rate is zero after two half-lives.Which one,if either,is correct,and why?

When a nucleus at rest spontaneously splits into fragments of mass m₁ and m₂,the ratio of the momentum of m₁ to the momentum of m₂ is

For large mass number nuclei which are stable,the ratio of protons to neutrons 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?

Heavy nuclei are unstable because

Two nuclei may have equal Z,but different A,because they contain

Exam 30: Nuclear Physics

Radiant energy reaching the Earth from the sun is not sufficient to keep the Earth's surface temperature comfortable for life.Of the following,the most likely source of the additional thermal energy is from

A pure sample of 226Ra contains 2.0 * 1014 atoms of the isotope.If the half-life of 226Ra = 1.6 * 103 years,what is the decay rate of this sample? (1 Ci = 3.7 * 1010 decays/s)

The chart below shows part of the radioactive series beginning with the isotope 90232Th{ } _ { 90 } ^ { 232 } \mathrm { Th }90232​Th .The isotope marked with an X is

Rutherford's experiment,in which he fired alpha particles of 7.7 MeV kinetic energy at a thin gold foil,showed that nuclei were very much smaller than the size of an atom because

Calculate the binding energy per nucleon (MeV/nucleon) for tritium,( 13H{ } _ { 1 } ^ { 3 } \mathrm { H }13​H ) a radioactive isotope of hydrogen. Assume: M p = 1.007 825 u M n = 1.008 665 u M t = 3.016 05 u U = 1.66 *10-27 kg

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

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the disintegration constant (in s - 1) ?

What value of Z (atomic number) and A (mass number) result in the following alpha decay? 92238U→zAX+α{ } _ { 92 } ^ { 238 } U \rightarrow { } _ { z } ^ { A } X + \alpha92238​U→zA​X+α

What value of Z (atomic number) and A (mass number) result in the following gamma decay? 612C→zAX+γ{ } _ { 6 } ^ { 12 } \mathrm { C } \rightarrow { } _ { z } ^ { A } \mathrm { X } + \gamma612​C→zA​X+γ

Two nuclei which share the same mass number A always are (Hint: Eliminate any wrong answers. )

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 radius of a classical electron (re = kee2/mec2 = 2.8 * 10 - 15 m) to the radius of a 4He nucleus (r = r0A1/3) is

In which of the following decays does the atomic mass number of the daughter nucleus differ from that of the parent nucleus?

When a fast neutron collides with a hydrogen or deuterium nucleus,the most likely result is that

Homer says that we can safely use nuclear power because all radioactive nuclei are gone after two half-lives.Marge says that only the decay rate is zero after two half-lives.Which one,if either,is correct,and why?

When a nucleus at rest spontaneously splits into fragments of mass m1 and m2,the ratio of the momentum of m1 to the momentum of m2 is

For large mass number nuclei which are stable,the ratio of protons to neutrons 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?

Heavy nuclei are unstable because

Two nuclei may have equal Z,but different A,because they contain

A pure sample of ²²⁶Ra contains 2.0 * 10¹⁴ atoms of the isotope.If the half-life of ²²⁶Ra = 1.6 * 10³ years,what is the decay rate of this sample? (1 Ci = 3.7 * 10¹⁰ decays/s)

Calculate the binding energy per nucleon (MeV/nucleon) for tritium,( ${ } _ { 1 } ^ { 3 } \mathrm { H }$ ) a radioactive isotope of hydrogen. Assume: M_p = 1.007 825 u M_n = 1.008 665 u M_t = 3.016 05 u U = 1.66 *10^-²⁷ kg

The isotope,tritium,has a half-life of 12.3 years.Assume we have 10 kg of the substance.What will be the disintegration constant (in s ^- ¹) ?

What value of Z (atomic number) and A (mass number) result in the following alpha decay? ${ } _ { 92 } ^ { 238 } U \rightarrow { } _ { z } ^ { A } X + \alpha$

What value of Z (atomic number) and A (mass number) result in the following gamma decay? ${ } _ { 6 } ^ { 12 } \mathrm { C } \rightarrow { } _ { z } ^ { A } \mathrm { X } + \gamma$

The ratio of the radius of a classical electron (r_e = k_ee²/m_ec² = 2.8 * 10 ^- ¹⁵m) to the radius of a ⁴He nucleus (r = r₀A^1/3) is

When a nucleus at rest spontaneously splits into fragments of mass m₁ and m₂,the ratio of the momentum of m₁ to the momentum of m₂ 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?