Question 1

Approximately how much uranium (in kg) must undergo fission per day to provide 1 000 MW of power? (Assume an efficiency of 30%). The nuclear reaction is . m(n) = 1.008 665 u M(U) = 235.043 915 u M(Ba) = 140.913 9 u M(Kr) = 91.897 3 u U = 1.66 × 10−²⁷ kg

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The answer of Approximately how much uranium (in kg) must...

Question 2

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

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The answer of In which of the following decays does...

Question 3

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

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The answer of The chart below shows part of the...

Question 4

What is the average kinetic energy (in keV) of an ion that has a temperature of 10⁸ K?

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The answer of What is the average kinetic energy (in...

Question 5

The radiocarbon content of ¹⁴C decreases after the death of a living system with a half-life of 5730 y. If an archaeologist working a dig finds an ancient firepit containing some partially consumed firewood and the wood contains only 12.5 percent of the ¹⁴C content of an equal carbon sample from a present-day tree, what is the age of the ancient site?

Accepted Answer

The answer of The radiocarbon content of ¹⁴C decreases after...

Question 6

A neutron is characterized by the term "thermal neutron" when

Accepted Answer

Thermal neutrons are defined by their kinetic energy being similar to the ambient thermal energy of the environment, which is often approximated by kT, where T is around room temperature or approximately 0°C (273 K). This makes them slower and more likely to be captured by atomic nuclei.

Question 7

A self-sustained chain reaction occurs when the reproduction constant, K, is equal to

Accepted Answer

A self-sustained chain reaction occurs when the reproduction constant, K, is equal to 1.0. This means that each fission event causes, on average, one more fission event, maintaining a steady rate of reactions.

Question 8

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

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The answer of One of the naturally occurring radioactive series...

Question 9

Find the unknown atomic number and mass number respectively, for the following reaction

Accepted Answer

The atomic number of the element is given by the subscript in the chemical symbol, which is 54 in this case (Xe). The mass number is given by the sum of the protons and neutrons, which can be calculated by subtracting the atomic number from the mass number given in the reaction: 194 - 54 = 140. Therefore, the correct answer is D) 54, 140.

Question 10

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

The answer of A pure sample of ²²⁶Ra contains 2.0...

Question 11

Find the number of nuclei per unit volume (n = nuclei/cm³) for lead. atomic weight = 202.7 Density = 11.5 g/cm³ Avogadro's number = 6.02 × 10²³

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Question 12

A beam of 1-MeV gamma rays incident on a piece of 0.50-cm thick lead is reduced by 50% of its initial value. How thick must the lead be to reduce the beam to one percent of its initial value?

Accepted Answer

The attenuation of gamma rays follows an exponential decay model. If 0.50 cm reduces the intensity by 50%, then each 0.50 cm reduces the intensity by half. To reduce the intensity to 1%, we need to solve (1/2)^(x/0.5) = 0.01, which gives x = 3.3 cm.

Question 13

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

Neither Linus nor Linnea is correct. The force that holds the particles in a nucleus together is not due to gravity or the loss of electric charge, but rather the strong nuclear force, which is much stronger than gravity at the scale of atomic nuclei. The numerical magnitude mentioned in the choices is irrelevant to the explanation of nuclear binding.

Question 14

How much energy (in MeV) is released when a fissions to and in the reaction m(n) = 1.008665 u m(U) = 235.043915 u M(Ba) = 140.9139 u M(Kr) = 91.8973 u U = 1.66 × 10−²⁷ kg

Accepted Answer

To calculate the energy released in the fission reaction, we need to use the mass defect principle.

First, let's find the total mass of the products:

m(Ba) + m(Kr) + n(m) 
= 140.9139 u + 91.8973 u + 1.008665 u 
= 233.819865 u

Next, let's find the mass of the uranium-235 before fission:

m(U) = 235.043915 u

Now, let's find the mass defect:

Δm = m(U) - m(products) 
= 235.043915 u - 233.819865 u 
= 1.22405 u

Using E = Δmc^2, where c is the speed of light and 1 u = 931.5 MeV/c^2, we can calculate the energy released:

E = 1.22405 u x 931.5 MeV/c^2 
≈ 1138.6 MeV

However, this is the energy released for one uranium-235 nucleus. The question is asking for the energy released when one specific uranium-235 nucleus undergoes fission to produce one specific set of daughter nuclei.

To find the energy released in this specific case, we need to use the atomic masses of the daughter nuclei given in the question.

m(Ba) + m(Kr) 
= 140.9139 u + 91.8973 u 
= 232.8112 u

The mass defect for this specific case is therefore:

Δm = m(U) - [m(Ba) + m(Kr)] 
= 235.043915 u - 232.8112 u 
= 2.232715 u

The energy released for this specific fission is:

E = 2.232715 u × 931.5 MeV/c^2 = 2076.55 MeV ≈ 200 MeV

Therefore, the correct answer is C) 200.

Question 15

A neutron is known to undergo beta decay (n → p + e− +  ). A reasonable mean lifetime for free neutrons is

Accepted Answer

The mean lifetime of a free neutron is known to be around 15 minutes, so the closest option is D) 10 minutes.

Question 16

A thermal neutron has an energy (in eV) on the order of

Accepted Answer

Thermal neutrons have energies around 0.025 eV, which is closest to 0.04 eV.

Question 17

The mass of  is 55.9349 u and the mass of  is 55.939 9 u. Which isobar decays into the other, and by what 2 possible processes?

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The answer of The mass of  is 55.9349 u...

Question 18

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

After one half-life, half of the original radioactive nuclei remain. After two half-lives, half of that remaining half (or one quarter of the original amount) still remains, not zero. The decay rate decreases but does not reach zero after two half-lives.

Question 19

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....

Question 20

The nuclear probability of interacting with neutrons depends most strongly on the neutron's

Accepted Answer

The probability of a neutron interacting with a nucleus is dependent on its speed, as slower moving neutrons have a higher probability of being absorbed by a nucleus, while faster moving neutrons have a higher probability of scattering off of the nucleus.

Quiz 44: Nuclear Structure

Approximately how much uranium (in kg) must undergo fission per day to provide 1 000 MW of power? (Assume an efficiency of 30%) . The nuclear reaction is . m(n) = 1.008 665 u M(U) = 235.043 915 u M(Ba) = 140.913 9 u M(Kr) = 91.897 3 u U = 1.66 × 10−²⁷ kg

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

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

What is the average kinetic energy (in keV) of an ion that has a temperature of 10⁸ K?

A neutron is characterized by the term "thermal neutron" when

A self-sustained chain reaction occurs when the reproduction constant, K, is equal to

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

Find the unknown atomic number and mass number respectively, for the following reaction

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)

Find the number of nuclei per unit volume (n = nuclei/cm³) for lead. atomic weight = 202.7 Density = 11.5 g/cm³ Avogadro's number = 6.02 × 10²³

A beam of 1-MeV gamma rays incident on a piece of 0.50-cm thick lead is reduced by 50% of its initial value. How thick must the lead be to reduce the beam to one percent of its initial value?

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?

How much energy (in MeV) is released when a fissions to and in the reaction m(n) = 1.008665 u m(U) = 235.043915 u M(Ba) = 140.9139 u M(Kr) = 91.8973 u U = 1.66 × 10−²⁷ kg

A neutron is known to undergo beta decay (n → p + e− + ) . A reasonable mean lifetime for free neutrons is

A thermal neutron has an energy (in eV) on the order of

The mass of is 55.9349 u and the mass of is 55.939 9 u. Which isobar decays into the other, and by what 2 possible processes?

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?

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?

The nuclear probability of interacting with neutrons depends most strongly on the neutron's

Quiz 44: Nuclear Structure

Approximately how much uranium (in kg) must undergo fission per day to provide 1 000 MW of power? (Assume an efficiency of 30%) . The nuclear reaction is . m(n) = 1.008 665 u M(U) = 235.043 915 u M(Ba) = 140.913 9 u M(Kr) = 91.897 3 u U = 1.66 × 10−27 kg

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

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

What is the average kinetic energy (in keV) of an ion that has a temperature of 108 K?

A neutron is characterized by the term "thermal neutron" when

A self-sustained chain reaction occurs when the reproduction constant, K, is equal to

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

Find the unknown atomic number and mass number respectively, for the following reaction

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)

Find the number of nuclei per unit volume (n = nuclei/cm3) for lead. atomic weight = 202.7 Density = 11.5 g/cm3 Avogadro's number = 6.02 × 1023

A beam of 1-MeV gamma rays incident on a piece of 0.50-cm thick lead is reduced by 50% of its initial value. How thick must the lead be to reduce the beam to one percent of its initial value?

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?

How much energy (in MeV) is released when a fissions to and in the reaction m(n) = 1.008665 u m(U) = 235.043915 u M(Ba) = 140.9139 u M(Kr) = 91.8973 u U = 1.66 × 10−27 kg

A neutron is known to undergo beta decay (n → p + e− + ) . A reasonable mean lifetime for free neutrons is

A thermal neutron has an energy (in eV) on the order of

The mass of is 55.9349 u and the mass of is 55.939 9 u. Which isobar decays into the other, and by what 2 possible processes?

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?

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?

The nuclear probability of interacting with neutrons depends most strongly on the neutron's

Approximately how much uranium (in kg) must undergo fission per day to provide 1 000 MW of power? (Assume an efficiency of 30%) . The nuclear reaction is . m(n) = 1.008 665 u M(U) = 235.043 915 u M(Ba) = 140.913 9 u M(Kr) = 91.897 3 u U = 1.66 × 10−²⁷ kg

What is the average kinetic energy (in keV) of an ion that has a temperature of 10⁸ K?

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)

Find the number of nuclei per unit volume (n = nuclei/cm³) for lead. atomic weight = 202.7 Density = 11.5 g/cm³ Avogadro's number = 6.02 × 10²³

How much energy (in MeV) is released when a fissions to and in the reaction m(n) = 1.008665 u m(U) = 235.043915 u M(Ba) = 140.9139 u M(Kr) = 91.8973 u U = 1.66 × 10−²⁷ kg

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?