Deck 20: The Nucleus: a Chemists View

Question 1

Electron capture transforms into what nuclide?

A)
B)
C)
D)
E)

Answer 1

Question 2

The stable nuclide is formed from by a long series of $\alpha$ and $\beta$ decays. Which of the following nuclides could not be involved in this decay series?

A) Po-221
B) Pu-239
C) Tl-210
D) Ra-226
E) Pa-234

Answer 2

Pu-239

Question 3

Which of the following is a product of $\alpha$ decay of ?

A)
B)
C)
D)
E)

Answer 3

Question 4

An unstable isotope of Re-191 is a beta producer. What is the other product of the reaction?

A) W-191
B) Os-191
C) Os-190
D) Pt-192
E) Re-192

Question 5

The ratio of the atomic radius to the nuclear radius is approximately

A) 10⁵
B) 10^-5
C) 10^-15
D) 10²
E) 10¹⁵

Question 6

Which reaction will produce an isotope of the parent nuclide?

A) $\beta$ +?
B)
C) $\beta$ +?
D)
E)

Question 7

The U-238 nucleus decays to form Pb-206 by $\alpha$ and $\beta$ decays.

-Calculate the number of $\beta$ decays.

A) 4
B) 2
C) 8
D) 6
E) none of these

Question 8

The most likely decay mode (or modes) of the unstable nuclide would be

A) positron production.
B) ( $\alpha$ -particle production).
C) ( $\beta$ emission).
D) electron capture.
E) either positron production or electron capture or both.

Question 9

It is desired to determine the concentration of arsenic in a lake sediment sample by means of neutron activation analysis. The nuclide captures a neutron to form , which in turn undergoes $\beta$ decay. The daughter nuclide produces the characteristic $\gamma$ rays used for the analysis. What is the daughter nuclide?

A)
B)
C)
D)
E)

Question 10

is an unstable isotope. Which radioactive decay would be expected?

A)
B) ( $\alpha$ )
C) fission
D) ( $\beta$ )
E)

Question 11

Which of the following processes increases the atomic number by 1?

A) proton production
B) beta-particle production
C) gamma-ray production
D) alpha production
E) neutron-particle production

Question 12

The nuclide Bi-213 is the daughter nuclide resulting from the $\alpha$ decay of what parent nuclide?

A) At-217
B)
C) Tl-209
D) Fr-215
E) Hg-297

Question 13

Heavy nuclides with too few neutrons to be in the band of stability are most likely to decay by what mode?

A) ( $\alpha$ -particle production).
B) fission
C) ( $\beta$ production).
D) positron production
E) none of these

Question 14

The nuclide is radioactive. When one of these atoms decays, a series of $\alpha$ - and $\beta$ ^- -particle emissions occurs, taking the atom through many transformations to end up as an atom of . How many $\alpha$ particles are emitted in converting into ?

A) 8
B) 214
C) 4
D) 6
E) 2

Question 15

When undergoes $\beta$ emission, what are the products?

A) + $\beta$
B)
C) + $\beta$
D) + $\beta$
E) + $\beta$

Question 16

Which types of processes are likely when the neutron-to-proton ratio in a nucleus is too large?
I. $\alpha$ decay
II. $\beta$ decay
III.Positron production
IV.Electron capture

A) IV only
B) III, IV
C) II, III
D) I, II
E) II only

Question 17

Identify the missing particle in the following equation:

A)
B)
C)
D)
E) none of these

Question 18

What is the most likely decay for the Co-62 nucleus?

A) positron emission
B) ( $\gamma$ -ray emission)
C) ( $\beta$ decay)
D) ( $\alpha$ decay)
E) proton emission

Question 19

The U-238 nucleus decays to form Pb-206 by $\alpha$ and $\beta$ decays.

-Calculate the number of $\alpha$ decays.

A) 2
B) 4
C) 6
D) 8
E) none of these

Question 20

A radioactive isotope of vanadium, , decays by producing  particles and gamma rays. The nuclide formed has the atomic number

A) 23.
B) 21.
C) 22.
D) 24.
E) none of these

Question 21

The number of a certain radioactive nuclide present in a sample decays from 2.2 *10² to 6.2 *10¹ in 29 minutes. What is the half-life of this radioactive species?

A) 2.0 *10¹ minutes
B) 4.4 *10^-2 minutes
C) 1.6 * 10¹ minutes
D) 7.1 *10¹ minutes
E) 3.7 minutes

Question 22

What is the most likely decay for the Fe-53 nucleus?

A) ( $\gamma$ -ray emission)
B) ( $\alpha$ decay)
C) ( $\beta$ decay)
D) positron emission
E) two of these

Question 23

A 0.20-mL sample of a solution containing that produces 3.7 * 10³ cps is injected into the bloodstream of an animal. After circulatory equilibrium has been established, a 0.20-mL sample of blood is found to have an activity of 20 cps. Calculate the blood volume of the animal.

A) 18 mL
B) 180 mL
C) 11 mL
D) 37 mL
E) none of these

Question 24

The rate constant for the decay of a radioactive element is 3.20 * 10^-3/day. What is the half-life of this element?

A) 1.60 **10^-3 days
B) 3.13 * 10² days
C) 2.17 * 10² days
D) 1.56 * 10² days
E) 3.23 *10² days

Question 25

Radioactive elements decay via first-order kinetics. Consider a certain type of nucleus that has a rate constant of 2.4 *10^-2 h^-1. A sample contains 7.6 * 10⁸ radioactive nuclides. Calculate the time required to reduce that number to 1.6 *10⁸.

A) 11.4 h
B) 2.5 *10¹⁰ h
C) 6.5 * 10¹ h
D) 2.8 * 10¹ h
E) 5.1 * 10^-1 h

Question 26

The Cs-131 nuclide has a half-life of 30 years. After 120 years, about 3 g remain. The original mass of the Cs-131 sample is closest to

A) 30 g
B) 70 g
C) 60 g
D) 50 g
E) 40 g

Question 27

The half-life of ⁹⁰Sr is 28 years. How long will it take for a given sample of ⁹⁰Sr to be 86% decomposed?

A) 3.4 * 10¹ years
B) 2.6 years
C) 3.3 *10² years
D) 6.1 years
E) 7.9* 10¹ years

Question 28

The rate constant for the beta decay of a particular radioactive element is 2.70 *10^-2/day. What is the half-life of this nuclide?

A) 3.70 * 10¹ days
B) 3.90 * 10^-1 days
C) 1.85*10¹ days
D) 7.41*10² days
E) 2.57 *0¹ days

Question 29

Which of the following balanced equations is labeled incorrectly?

A) beta production:
B) bombardment:
C) alpha production:
D) fusion:
E) fusion:

Question 30

When the U-235 nucleus is struck with a neutron, the Ce-144 and Sr-90 nuclei are produced, along with some neutrons and beta particles.
How many beta particles are emitted?

A) 5
B) 6
C) 3
D) 2
E) 4

Question 31

What nuclide is necessary to balance the following fission reaction? __________

A)
B)
C)
D)
E)

Question 32

When the U-235 nucleus is struck with a neutron, the Ce-144 and Sr-90 nuclei are produced, along with some neutrons and beta particles.
How many neutrons are emitted?

A) 5
B) 6
C) 2
D) 3
E) 4

Question 33

A radioactive element has a half-life of 16 min. How many minutes will it take for the number of atoms present to decay to 1/8th of the initial value?

A) 450 min
B) 48 min
C) 2.0 min
D) 128 min
E) 250 min

Question 34

Breeder reactors are used to convert the nonfissionable nuclide into a fissionable product. Neutron capture of the is followed by two successive beta decays. What is the final fissionable product?

A)
B)
C)
D)
E)

Question 35

Radioactive tracers are useful in studying very low concentrations of chemical species. A chemist has a sample of HgI₂ in which part of the iodine is the radioactive nuclide of mass 131, so that the count rate is 5.0 * 10¹¹ counts per minute per mole of I. The solid mercuric iodide is placed in water and allowed to come to equilibrium. Then 100 mL of the solution is withdrawn, and its radioactivity is measured and found to give 22 counts per minute. What is the molar concentration of iodide ion in the solution?

A) 1.1*10^-11
B) 1.1 * 10^-9
C) 1.1 *10^-10
D) 4.4 * 10^-10
E) 4.4* 10^-11

Question 36

It is desired to determine the blood volume of a live mouse. To do this, 0.10 mL of a saline suspension of red blood cells labeled with is injected into the tail vein. Before injection the gamma rays were counted for this 0.10-mL solution, and the count rate was found to be 1.0 *10⁴ cpm. After a sufficient time for the blood to be thoroughly mixed, 0.10 mL of blood is removed and counted. The sample is found to have a count rate of 476 cpm. What is the approximate blood volume of the mouse?

A) 0.48 mL
B) 4.7 mL
C) 21 mL
D) 4.8 mL
E) 2.1 mL

Question 37

Radioactive elements decay via first-order kinetics. Consider a certain type of nucleus that has a rate constant of 1.6 *10^-2 h^-1. A sample contains 7.9 * 10⁸ radioactive nuclides. Calculate the time required for 63% of the nuclides to decompose.

A) 1.3 * 10¹ h
B) 1.3* 10^-1 h
C) 2.7 * 10¹ h
D) 2.9 * 10¹ h
E) 6.2 *10¹ h

Question 38

When the Pd-106 nucleus is struck with an alpha particle, a proton is produced along with a new element. What is this new element?

A) Cd-109
B) Ag-108
C) Ag-109
D) Cd-112
E) none of these

Question 39

When the U-235 nucleus is struck with a neutron, the Zn-72 and Sm-160 nuclei are produced, along with some neutrons. How many neutrons are emitted?

A) 2
B) 3
C) 4
D) 5
E) 6

Question 40

What is the number of half-lives needed for a radioactive element to decay to one-fourth of its original activity? (Choose the nearest number.)

A) 1
B) 4
C) 3
D) 5
E) 2

Question 41

Which statement is true about the following reaction?

A) No energy change is associated with the reaction.
B) Energy is released in the reaction.
C) Energy is absorbed in the reaction.
D) Not enough information is given for us to determine the energy change.

Question 42

The half-life of ⁹⁰Sr is 28.1 years. How long will it take a 10.9-g sample of ⁹⁰Sr to decompose to 0.18 g?

A) 1.0 *10¹ years
B) 7.2 *10¹ years
C) 1.7 *10² years
D) 4.6 *10^-1 years
E) 1.7 * 10³ years

Question 43

If a tree dies and the trunk remains undisturbed for 13,750 years, what percentage of the original ¹⁴C is still present? (The half-life of ¹⁴C is 5730 years.)

A) 2.20%
B) 19.0%
C) 45.0%
D) 5.20%

Question 44

The half-life for electron capture for is 1.3 billion years. What will be the ratio in a rock that is 4.5 billion years old?

A) 0.10
B) 0.091
C)10.
D)11.
E) 0.36

Question 45

The questions below refer to the following:
Iron-56, , has a binding energy per nucleon of 8.79 MeV. (1 MeV = 1.60 * 10^-13 J)

-Determine the difference in mass between 1 mol of iron-56 nuclei and the component nucleons of which it is made.

A) 5.27 * 10^-4 kg
B) 2.43* 10^-5 kg
C) 6.65 * 10^-5 kg
D) 7.21 * 10^-4 kg
E) 9.41 *10^-6 kg

Question 46

The smallest amount of radioactive material that will support a self-sustained reaction is called the

A) moderator.
B) critical mass.
C) molar mass.
D) supercritical mass.
E) subcritical mass.

Question 47

Which of the following is not a factor in determining the biological effects of radiation exposure?

A) the energy of the radiation
B) the age of the organism when the exposure occurs
C) the penetrating ability of the radiation
D) the ionizing ability of the radiation
E) the chemical properties of the radiation source

Question 48

The questions below refer to the following:
Iron-56, , has a binding energy per nucleon of 8.79 MeV. (1 MeV = 1.60 * 10^-13 J)

-Determine the amount of energy needed to "decompose" 1 mol of iron-56 nuclei.

A) 4.74 *10¹³ J
B) 3.47 * 10¹¹ J
C) 8.90 * 10¹¹ J
D) 1.13 *10¹⁴ J
E) 7.75 *10¹³ J

Question 49

Radioactive elements decay via first-order kinetics. Consider a certain type of nucleus that has a rate constant of 1.0 * 10^-3 h^-1. A sample contains 5.0 *10⁹ radioactive nuclides. Calculate the number of nuclides remaining after 39 days have passed.

A) 64
B) 7.8 * 10^-11
C) 2.0 * 10⁹
D) 5.0* 10⁹
E) 2.5 *10⁹

Question 50

One of the hopes for solving the world's energy problem is to make use of the fusion reaction How much energy is released when 1 mol of deuterium is fused with 1 mol of tritium according to the above reaction? The masses of the atoms and the neutrons are as follows: The speed of light is 2.9979 *10⁸ m/s.

A) 1.69 * 10¹² J
B) 5.63 *10⁸ J
C) 8.44 *10¹¹ J
D) 7.84 * 10⁴⁴ J
E) 56.3 J

Question 51

Consider the following process: Which statement describes $\Delta$ E for the process?

A) 1.15 * 10¹¹ J/mol is released.
B) 1.15 * 10¹⁴ J/mol is released.
C) 1.15 *10¹⁸ J/mol is absorbed.
D) 1.15* 10¹¹ J/mol is absorbed.
E) none of these

Question 52

Fresh rainwater or surface water contains enough tritium to show 5.5 decompositions per minute per 100. g of water. Tritium has a half-life of 12.3 years. You are asked to check a vintage wine claimed to have been produced in 1946. How many decompositions per minute should you expect to observe in 100. g of that wine?

A) 1.7
B) 0.035
C) 0.17
D) 181
E) 0.35

Question 53

The Br-82 nucleus has a half-life of about 1.0 *10³ minutes. If you needed at least 1.6 g of Br-82 and had ordered 29 g of NaBr (assuming all of the Br in the NaBr was Br-82), how many days could you wait for delivery?

A) 3.2 days
B) 1.2 days
C) 2.9 days
D) 2.6 days
E) 3.8 days

Question 54

Which of the following statements is true of the fission of uranium-235?

A) The nuclides produced are individually heavier than the uranium nuclide.
B) The ultimate nuclides produced are more stable than the uranium nuclide.
C) The electron is captured by the nucleus, which becomes unstable.
D) The products include neutrons.
E) two of these

Question 55

The half-life for electron capture for is 1.30 * 10⁹ years. What percent of the original remains after 3.90 *10⁹ years?

A) 12.5%
B) 75.0%
C) 25.0%
D) 33.3%
E) 50.0%

Question 56

Calculate $\Delta$ E in kilojoules per mole for the reaction Atomic masses: , , .

A) 0
B) +2.4 * 10⁶ kJ/mol
C) +4.6 * 10⁸ kJ/mol
D) -4.6 * 10⁸ kJ/mol
E) -2.4 *10⁶ kJ/mol

Question 57

A sample of wood from an Egyptian mummy case gives a ¹⁴C count of 9.1 cpm/gC (counts per minute per gram of carbon). How old is the wood? (The initial decay rate of ¹⁴C is 15.3 cpm/gC, and its half-life is 5730 years.)

A) 3.4 * 10³ years
B) 4.3 * 10³ years
C) 4.9*10³ years
D) 1.9 *10³ years
E) 3.0 *10³ years

Question 58

Use the following data to determine the expected ¹⁴C activity in the Shroud of Turin. The atmospheric activity of ¹⁴C is 15 cpm/gC (counts per minute per gram of carbon). Assume that the cloth was made in the year A.D. 24. The half-life of ¹⁴C is 5730 years.

A) 12 cpm/gC
B) 5.1 cpm/gC
C) 28 cpm/gC
D) 7.3 cpm/gC
E) 11 cpm/gC

Question 59

If more than one neutron from each fission event causes another fission event, the fission situation is described as

A) supercritical.
B) critical.
C) moderated.
D) subcritical.
E) none of these

Question 60

Calculate the change in energy, in kilojoules per mole, for the transmutation of radium from the given molar masses:

A) -4.7 * 10⁸ kJ/mol
B) -4.7 *10¹⁴ kJ/mol
C) +1.6 *10⁸ kJ/mol
D) -1.6 kJ/mol
E) -5.2 kJ/mol

Question 61

Radiocarbon dating is based on which decay process?

A)
B)
C)
D) All of the above
E) None of the above

Question 62

Explain how a particle accelerator works.

Question 63

Which of the following is not a charged species?

A) particle
B) particle
C) particle
D) all of the above
E) none of the above

Question 64

What is the result of a collision between an electron and a positron?

A) ( $\gamma$ rays)
B) x-rays
C) antimatter
D) a quark
E) all of the above are possible

Question 65

Distinguish alpha-particle production and beta-particle production, and provide an example of each.

Question 66

Discuss and explain the operation of a nuclear reactor.

Question 67

Discuss and explain the operation of a scintillation counter.

Question 68

Distinguish between a cyclotron and a linear accelerator.