Deck 19: The Nucleus: a Chemists View

Question 1

Which of the following processes decreases the atomic number by one?

A)gamma-ray production
B)electron capture
C)beta-particle production
D)positron production
E)at least two of the above processes

Answer 1

at least two of the above processes

Question 2

A radioactive isotope of vanadium, V,decays by producing a $\beta$ particle and gamma ray.The nuclide formed has the atomic number:

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

Answer 2

24

Question 3

Identify the missing particle in the following equation: U $\to$ He + ?

A) Pu
B) Th
C) Th
D) U
E)none of these

Answer 3

Th

Question 4

Which reaction will produce an isotope of the parent nuclide?

A) Po $\to$ He + ?
B) Br $\to$ n + ?
C) Ac $\to$ e^- + ?
D) N $\to$ e^- + ?
E) As + e^- $\to$ ?

Question 5

Nuclides with too many neutrons to be in the band of stability are most likely to decay by what mode?

A)alpha emission
B)fission
C)positron production
D)electron capture
E)beta emission

Question 6

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) Se
B) Ge
C) Ga
D) Se
E) Se

Question 7

The Fe-56 nucleus is known to be stable.Answer the following questions.

-What is the most likely decay for the Fe-59 nucleus?

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

Question 8

Electron capture transforms Be into what nuclide?

A) Li
B) B
C) Li
D) B
E) C

Question 9

Electron capture transforms K into what nuclide?

A) Ca
B) Ar
C) He
D) K^-
E) Ca

Question 10

The nuclide N is unstable.What type of radioactive decay would be expected?

A) e
B) e
C)( $\sigma$ )
D)( $\alpha$ )
E) n

Question 11

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 12

When Np undergoes $\beta$ ^- emission,the products are:

A) U + e^-
B) Pu + e^-
C) U + e^-
D) Pa + He
E) Np + e^-

Question 13

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

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

Question 14

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

A)10^-5
B)10⁵
C)10²
D)10¹⁵
E)10^-15

Question 15

The nuclide Th 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 Pb.How many $\alpha$ particles are emitted in converting Th into Pb?

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

Question 16

If Pb undergoes a beta decay and the product of this decay undergoes another beta decay,which nuclide is produced?

A) Bi
B) Pb
C) Po
D) Bi
E) Pb

Question 17

The Fe-56 nucleus is known to be stable.Answer the following questions.

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

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

Question 18

The nuclide Tl is the daughter nuclide resulting from the $\alpha$ decay of what parent nuclide?

A) Pb
B) Au
C) Hg
D) Bi
E) He

Question 19

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

A) Th
B) Np
C) Pa
D) U
E) Pu

Question 20

An unstable isotope of rhenium,¹⁹¹Re,has a half-life of 9.8 minutes and is a beta producer.What is the other product of the reaction?

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

Question 21

The so-called "magic numbers" of protons and neutrons produce special chemical stability.

Question 22

As atomic mass increases,the proton/neutron ratio of stable nuclides decreases.

Question 23

Consider a certain type of nucleus that has a rate constant of 2.95 $\times$ 10^-2 min^-1.Calculate the time required for the sample to decay to one-fourth of its initial value.

A)2.95 min
B)0.0590 min
C)23.5 min
D)29.4 min
E)47.0 min

Question 24

The number of a certain radioactive nuclide present in a sample decays from 160.to 20.in 39 minutes.What is the half-life of this radioactive species?

A)8 minutes
B)13 minutes
C)18 minutes
D)23 minutes
E)28 minutes

Question 25

The number of half-lives needed for a radioactive element to decay to about 6% of its original activity is (choose nearest number):

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

Question 26

The Cs-131 nuclide has a half-life of 30.years.After 144 years,about 3.0 grams remain.The original mass of the Cs-131 sample is closest to

A)167 g
B)42 g
C)84 g
D)292 g
E)100 g

Question 27

The half-life of a sample has been defined as the time it takes for half of a sample to decay.The fifth-life can be defined as the time it takes for one-fifth of a sample to decay.Given these definitions,calculate the fifth-life of a sample that has a half-life of 26 years.

A)8.4 years
B)60 years
C)17 years
D)29 years
E)42 years

Question 28

The half-life of is 28.1 years.How long will it take a 10.0-g sample of to decompose to 0.23 g?

A)102 years
B)306 years
C)153 years
D)229 years
E)none of these

Question 29

The rate constant for the beta decay of thorium-234 is 2.882 $\times$ 10^-2 / day.What is the half-life of this nuclide?

A)48.09 days
B)1.218 days
C)0.693 days
D)24.05 days
E)96.18 days

Question 30

The rate constant for the decay of is 4.234 $\times$ 10^-3 / day.What is the half-life of

A)81.84 days
B)163.7 days
C)327.4 days
D)409.2 days
E)none of these

Question 31

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

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

Question 32

The half-life of is 28 years.How long will it take for a given sample of to be 89% decomposed?

A)9.0 half-lives
B)5 years
C)89 years
D)2.2 years
E)none of these

Question 33

A radioactive sample has an initial activity of 2.00 $\times$ 10⁶ cpm (counts per minute),and after 4.0 days,its activity is 9.0 $\times$ 10⁵ cpm.What is its activity after 29 days?

A)8.7 cpm
B)6.1 $\times$ 10³ cpm
C)3.3 $\times$ 10² cpm
D)1.5 $\times$ 10^-9 cpm
E)none of these

Question 34

A radioactive element has a half-life of 1.6 hours.How many hours will it take for the number of atoms present to decay to one-sixteenth of the initial value?

A)26
B)13
C)6.4
D)0.15
E)16

Question 35

A certain radioactive sample contains 2.4 $\times$ 10³ nuclides at a certain time (t = 0);3.0 h later the sample contains 6.0 $\times$ 10² nuclides.

-The value of the rate constant for this process is:

A)2.2 h^-1
B)4.6 $\times$ 10^-1 h^-1
C)1.6 h^-1
D)3.0 h^-1
E)none of these

Question 36

Consider a certain type of nucleus that has a half-life of 32 min.Calculate the percent of original sample of nuclides remaining after 2.5 hours have passed.

A)96%
B)40%
C)6.9%
D)3.9%
E)3.2%

Question 37

The Br-82 nucleus has a half-life of about 1.0 $\times$ 10³ minutes.If you wanted 2.2 g of Br-82 and the delivery time was three days,about how much NaBr should you order (assuming all of the Br in the NaBr was Br-82)?

A)2.2 g
B)4.4 g
C)4.0 g
D)57 g
E)7.8 g

Question 38

Consider a certain type of nucleus that has a half-life of 32 min.Calculate the time required for 52% of the nuclides to decompose.

A)30 min
B)21 min
C)49 min
D)42 min
E)34 min

Question 39

A certain radioactive sample contains 2.4 $\times$ 10³ nuclides at a certain time (t = 0);3.0 h later the sample contains 6.0 $\times$ 10² nuclides.

-For this sample the ratio of the decay rates at t = 0 to t = 3.0 h is:

A)1.0
B)8.0
C)4.0
D)16
E)none of these

Question 40

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

-Calculate the number of $\beta$ decays.

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

Question 41

A 0.20-mL sample of a solution containing H that produces 3.7 $\times$ 10³ cps is injected into the bloodstream of an animal.After allowing circulatory equilibrium to be established,a 0.20-mL sample of blood is found to have an activity of 37 cps.Calculate the blood volume of the animal.

A)0.50 L
B)20 mL
C)10 mL
D)100 mL
E)none of these

Question 42

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 24 A.D.The half-life of ¹⁴C is 5730 years.

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

Question 43

In the following nuclear equation,identify the missing product: Ca + $\alpha$ $\to$ __________ + H

A) Ti
B) Sc
C) Ti
D) Ar
E)none of these

Question 44

One of the hopes for solving the world's energy problem is to make use of the fusion reaction: H + H $\to$ He + n + energy How much energy is released when one mole of deuterium is fused with one mole of tritium according to the above reaction? The masses of the atoms and the neutrons are: H = 2.0140 amu H = 3.01605 amu He = 4.002603 amu n = 1.008665 amu
The speed of light is 2.9979 $\times$ 10⁸ m/s

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

Question 45

Identify the missing particle in the following nuclear equation: Al + __________ $\to$ Na + $\alpha$

A) n
B) n
C) e
D) e
E)2 n

Question 46

Consider the following process:


Which statement describes $\Delta$ E for the process?

A)1.15 $\times$ 10¹¹ J/mol are released.
B)1.15 $\times$ 10¹⁴ J/mol are released.
C)1.15 $\times$ 10¹⁸ J/mol are absorbed.
D)1.15 $\times$ 10¹¹ J/mol are absorbed.
E)None of these.

Question 47

An archaeological sample contains 0.739 g of lead-206 and 2.328 g of uranium-238.Assume that all the lead now present in the rock came from the radioactive decay of the uranium and that no appreciable amounts of other radioactive nuclides are present in the sample.The decay rate constant for the uranium is 1.54 $\times$ 10^-10/year.What is the age of the sample?

A)8.54 $\times$ 10⁹ years
B)8.81 $\times$ 10⁸ years
C)2.03 $\times$ 10⁹ years
D)6.51 $\times$ 10⁹ years
E)none of these

Question 48

If a tree dies and the trunk remains undisturbed for 13,261 years,what percentage of original is still present? (half-life of = 5730 years)

A)79.9%
B)20.1%
C)40.2%
D)30.2%
E)2.31%

Question 49

Calculate $\Delta$ E in kilojoules per mole for the following reaction: Th $\to$ He + Ra Atomic masses: ²³⁰Th = 230.0332,⁴He = 4.00260,²²⁶Ra = 226.02544.

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

Question 50

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 Fe is injected into the tail vein.Before injection,the gamma rays were counted for this 0.10-mL solution and the count rate found to be 1.0 $\times$ 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 539 cpm.What is the approximate blood volume of the mouse?

A)0.54 mL
B)19 mL
C)5.4 mL
D)5.3 mL
E)1.9 mL

Question 51

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 $\times$ 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 $\times$ 10^-9
B)4.4 $\times$ 10^-10
C)1.1 $\times$ 10^-10
D)1.1 $\times$ 10^-11
E)4.4 $\times$ 10^-11

Question 52

The I-131 nuclide has a half-life of 8.0 days.If you originally have a 1.8-kg sample,after 1.4 months you will have approximately

A)95 g
B)62 g
C)71 g
D)47 g
E)less than 1 g

Question 53

A sample of wood from an Egyptian mummy case gives a count of 7.8 cpm/gC (counts per minute per gram of carbon).How old is the wood? (The initial decay rate of is 15.3 cpm/g C,and its half-life is 5730 years. )

A)2785 yr
B)8071 yr
C)5571 yr
D)6621 yr
E)none of these

Question 54

The half-life for electron capture for is 1.3 billion years.What will be the / ratio in a rock that is 5.1 billion years old?

A)0.066
B)14
C)0.071
D)3.9
E)15

Question 55

Calculate the change in energy in kJ/mol for the transmutation of radium from the given molar masses:

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

Question 56

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

Question 57

If one mole of oxygen-16 were formed from protons and neutrons,0.1366 g of mass would be lost.What can best account for this loss?

A)When fission occurs,the nuclei remaining always has a smaller mass.
B)Converting from the atomic scale (in amu's)to the macroscopic scale (in grams)can often cause minor errors to occur.
C)The process was so exothermic,the system lost energy,which meant that it also lost mass.
D)This is impossible because of the Law of Conservation of Matter (so mass must be conserved).
E)Both A and C are correct.

Question 58

An archaeological sample contains 0.743 g of lead-206 and 2.145 g of uranium-238.Assume that all the lead now present in the rock came from the radioactive decay of the uranium and that no appreciable amounts of other radioactive nuclides are present in the sample.The decay rate constant for the uranium is 1.537 $\times$ 10^-10/ year.Determine the half-life of the uranium.

A)4.509 $\times$ 10⁹ years
B)1.065 $\times$ 10^-10 years
C)depends on the age of the sample
D)depends on the organic content of the sample
E)two of these

Question 59

Identify the missing particle in the following nuclear equation: Am + He $\to$ __________ + 2 n

A) Bk
B) Bk
C) Bk
D) Bk
E) Bk

Question 60

The half-life for electron capture for is 1.30 $\times$ 10⁹ years.What percent of the original remains after 3.24 $\times$ 10⁹ years?

A)82.2%
B)17.8%
C)75.7%
D)24.3%
E)44.4%

Question 61

The lead-208 nucleus has a mass defect of 1.714 g/mol. Determine the binding energy per nucleon for lead-208 nuclei.(1 MeV is 1.602 $\times$ 10^-13 J).

A)1.597 $\times$ 10^-4 MeV
B)1.597 $\times$ 10³ MeV
C)19.47 MeV
D)24.68 MeV
E)7.677 MeV

Question 62

In the following fission reaction,identify the other product: U + n $\to$ I + 2 n + __________

A) Y
B) Y
C) Mo
D) Mo
E) Zr

Question 63

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 64

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

A) Pu
B) Ra
C) U
D) Pu
E) Np

Question 65

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

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

Question 66

Which of the following balanced equations is labeled incorrectly?

A)fission: Bi + He $\to$ At + 2 n
B)fusion: H + H $\to$ H + H
C)bombardment: Pu + n $\to$ Am + e
D)beta production: U $\to$ Np + e
E)all correctly labeled

Question 67

What nuclide is necessary to balance the following fission reaction? U + n $\to$ 3 n + Ba + __________

A) Br
B) Kr
C) Rb
D) Kr
E) Sr

Question 68

Iron-56 ( Fe)has a binding energy per nucleon of 8.79 MeV.(1MeV is 1.60 $\times$ 10^-13 J). Determine the difference in mass between one mole of iron-56 nuclei and the component nucleons of which it is made.

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

Question 69

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

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

Question 70

The mass defect arises because the sum of masses of the component nucleons is less than that of the nucleus.

Question 71

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

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

Question 72

Which of the following statements (A-D)is false?

A)The process of splitting a heavy nucleus into two nuclei with smaller mass numbers is called fission.
B)A beta particle is a particle with the same mass as the electron but opposite charge.
C)Nitrogen can be changed into oxygen by bombarding it with alpha particles.
D)Archaeologists use radioactivity to determine the age of some artifacts and rocks.
E)All of the above statements are true.

Question 73

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

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

Question 74

What component of a nuclear reactor moderates the rate of the reaction?

A)steam turbine
B)control rods
C)cooling water
D)containment shell
E)cyclotron

Question 75

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

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

Question 76

Radioactivity is not useful for:

A)Dating artifacts and rocks.
B)Producing electricity.
C)Tracing pathways in biological systems.
D)Making chemicals like sulfuric acid.
E)Radioactivity is useful for all of the above.

Question 77

Which statement about fusion is incorrect?

A)Fusion requires starting nuclides that are difficult to find on Earth,which is a problem for scientists.
B)Studying fusion is a worthwhile research endeavor because this process could be used as an alternative energy source.
C)Fusion requires a very high temperature in order to begin,which is a problem for scientists.
D)In fusion,two nuclei must be traveling fast enough to overcome the electrostatic repulsion and "fuse" the particles into a new nucleus.
E)Both A and C are incorrect.

Question 78

The bismuth-209 nucleus has a binding energy per nucleon of 7.6514 MeV.(1 MeV is 1.60 $\times$ 10^-13 J).Determine the difference in mass between one mole of bismuth-209 nuclei and the component nucleons of which it is made.

A)1.71 $\times$ 10^-3 kg
B)3.92 $\times$ 10^-8 kg
C)8.20 $\times$ 10^-6 kg
D)2.56 $\times$ 10^-10 kg
E)6.81 $\times$ 10^-4 kg

Question 79

How much energy is released when 5.00 metric tons of ²H₂ gas undergoes nuclear fusion? (1 metric ton = 1000 kg,c = 2.9979 $\times$ 10⁸ m/s,1 amu = 1.66054 $\times$ 10^-27 kg)
²H + ²H $\to$ ³He + ¹n
Particle
Mass (amu) 1.008665 2.01400 3.01603

A)7.37 $\times$ 10¹⁷ J
B)2.71 $\times$ 10^-18 J
C)5.39 $\times$ 10⁶⁴ J
D)3.69 $\times$ 10¹⁷ J
E)2.67 $\times$ 10⁷¹ J

Question 80

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 at which the exposure occurs
C)the penetrating ability of the radiation
D)the chemical properties of the radiation source
E)the ionizing ability of the radiation