Deck 19: Nuclear Chemistry: Applications to Energy and Medicine

Question 1

One of the last steps in the disintegration of uranium is . What particle is emitted in this reaction?

A)( particle)
B)neutron
C)proton
D)electron
E)positron

Answer 1

electron

Question 2

Which of the following nuclides are most likely to be unstable because they have too many neutrons?
I. nitrogen-15
II. boron-8
III. oxygen-18
IV. fluorine-19
V. magnesium-28

A)I and II
B)II and III
C)III and V
D)III, IV, and V
E)all of these

Answer 2

III and V

Question 3

The mass of an atomic nucleus is ________ the sum of the masses of its constituent nucleons (protons and neutrons).

A)always greater than
B)always less than
C)always the same as
D)sometimes greater than and sometimes smaller than
E)never smaller than

Answer 3

always less than

Question 4

Which of the following nuclides are most likely to be unstable because they have too many neutrons?
I. carbon-14
II. sodium-24
III. silicon-26
IV.aluminum-27
V. phosphorus-31

A)I only
B)I and II
C)II and III
D)III, IV, and V
E)all of these

Question 5

Which one of the following statements is not correct?

A)Carbon-10 is unstable because it has too few neutrons.
B)All nuclides with Z  83 decay into nuclides with smaller Z values.
C)Generally, the number of neutrons in a nuclide is equal to or less than the atomic number.
D)As the atomic number increases, the ratio of neutrons to protons in a nuclide increases.
E)It is very unusual to find a nuclide with an odd number of protons and an odd number of neutrons.

Question 6

The heaviest elements will generally have a neutron/proton ratio about equal to ________

A)0.5.
B)0.8.
C)1.0.
D)1.3.
E)1.5.

Question 7

The isotope "belt of stability" is an area in a plot of ________

A)nuclear binding energy versus atomic number.
B)isotopic strength versus isotopic weakness.
C)nuclear mass versus mass number.
D)neutron number versus atomic number.
E)mass number versus atomic number.

Question 8

The heaviest stable nucleus is an isotope of ________

A)platinum.
B)gold.
C)lead.
D)bismuth.
E)xenon.

Question 9

The most naturally abundant nuclides are those that ________

A)have an odd number of protons and an odd number of neutrons.
B)have an even number of protons and an even number of neutrons.
C)have noble gas configurations of electrons.
D)can be produced by fission reactions.
E)can be produced by fusion reactions.

Question 10

The mass of a particular isotope is given by ________

A)the mass number.
B)adding the masses of protons, neutrons, and electrons.
C)measuring it.
D)dividing the mass number by 6.02  10²³.
E)dividing the molar mass of the element by 6.02  10²³.

Question 11

Which element has stable isotopes with the largest ratio of neutrons to protons?

A)H
B)C
C)I
D)Sr
E)Ca

Question 12

The peak in nuclear binding energy/nucleon occurs for an isotope of ________

A)helium.
B)iron.
C)uranium.
D)carbon.
E)lead.

Question 13

The first step in the disintegration of uranium is . What particle is emitted in this reaction?

A)( particle)
B)neutron
C)proton
D)electron
E)( ray)

Question 14

Calculate the nuclear binding energy per nucleon for the copper-63 isotope. Here are some helpful data:

A)1.40235  10 ^12 J/nucleon
B)3.16577  10 ^9 J/nucleon
C)4.23566  10 ^12 J/nucleon
D)8.83480  10 ^11 J/nucleon
E)9.24913  10 ^15 J/nucleon

Question 15

Which process converts a neutron into a proton?

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

Question 16

Light elements with Z  20 generally have a neutron/proton ratio about equal to ________

A)0.5.
B)0.8.
C)1.0.
D)1.3.
E)1.5.

Question 17

Calculate the nuclear binding energy per nucleon for the beryllium-8 isotope. Here are some helpful data:

A)1.2035  10 ^6 J/nucleon
B)1.08479  10 ^9 J/nucleon
C)1.1317  10 ^12 J/nucleon
D)8.7266  10 ^12 J/nucleon
E)1.08479  10 ^15 J/nucleon

Question 18

Which one of the following statements is not correct?

A)Oxygen-15 is unstable because it has too few neutrons.
B)Nucleons are held together in a nuclide by the electromagnetic force.
C)All nuclides with Z  83 decay into more stable nuclides with smaller Z values.
D)As the atomic number increases, the ratio of neutrons to protons in a nuclide increases.
E)Generally, the number of neutrons in a nuclide equals the number of protons, or nearly so, when the atomic number is small, i.e., Z  18.

Question 19

All elements with Z  83 are ________

A)synthetic.
B)produced by nuclear fission.
C)radioactive.
D)not found in nature.
E)unreactive.

Question 20

What repulsive forces must be overcome for any element other than hydrogen to exist?

A)The repulsion between neutrons and other neutrons.
B)The repulsion between protons and other protons.
C)The repulsion between protons and neutrons.
D)The repulsion between positrons and electrons.
E)The repulsion between neutrons and electrons.

Question 21

Which graph below illustrates  decay?

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

Question 22

Which graph below illustrates positron emission?

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

Question 23

Fill in the missing nuclide to balance the following nuclear equation.

A)
B)
C)
D)
E)

Question 24

Which graph below illustrates neutron capture followed by decay?

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

Question 25

Which process converts a proton into a neutron?

A)beta emission
B)electron capture
C)alpha emission
D)gamma emission
E)neutron emission

Question 26

Which graph below illustrates decay?

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

Question 27

Beta emission is associated with ________

A)conversion of a neutron to a proton.
B)conversion of a proton to a neutron.
C)increase in mass number.
D)decrease in mass number.
E)emission of  rays.

Question 28

Nitrogen-13 decays by positron emission to produce ________

A)carbon-13.
B)oxygen-17.
C)boron-11.
D)carbon-14.
E)boron-13.

Question 29

K-capture is associated with ________

A)conversion of a neutron to a proton.
B)conversion of a proton to a neutron.
C)increase in mass number.
D)decrease in mass number.
E)emission of  rays.

Question 30

Thallium-206 decays by  decay to produce ________

A)gold-202.
B)lead-206.
C)polonium-209.
D)mercury-206.
E)platinum-208.

Question 31

Cobalt-56 decays by emitting a positron. What is the product?

A)cobalt-55
B)cobalt-56
C)nickel-56
D)iron-56
E)iron-55

Question 32

Polonium-210, which decays by  emission, is a fatal toxin. What is the product nuclide from this nuclear process?

A)bismuth-210
B)astatine-210
C)lead-206
D)bismuth-209
E)radon-206

Question 33

Positron emission is associated with ________

A)conversion of a neutron to a proton.
B)conversion of a proton to a neutron.
C)increase in mass number.
D)decrease in mass number.
E)emission of  rays.

Question 34

Fill in the missing nuclide to balance the following nuclear equation.

A)
B)
C)
D)
E)

Question 35

Which process converts a proton into a neutron?

A)beta emission
B)positron emission
C)alpha emission
D)gamma emission
E)neutron emission

Question 36

Cobalt-60 decays to nickel-60. What particle is emitted?

A)proton
B)neutron
C)electron
D)positron
E)alpha

Question 37

When a nucleus undergoes radioactive decay, the new atomic number ________
I. can be greater than the original atomic number.
II. can be the same as the original atomic number.
III. can be less than the original atomic number.
IV. must be the same as the original atomic number.

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

Question 38

When a nucleus undergoes radioactive decay, the new mass number is ________

A)always less than the original mass number.
B)always the same as the original mass number.
C)always more than the original mass number.
D)never less than the original mass number.
E)never more than the original mass number.

Question 39

Radon-220 decays to polonium-216. What particle is emitted?

A)beta
B)positron
C)neutron
D)alpha
E)gamma

Question 40

Which graph below illustrates electron capture?

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

Question 41

In a Geiger counter, which is used to detect radioactivity, a particle produced by radioactive decay ________

A)ionizes an inert gas to produce a pulse of electrical current.
B)heats up an inert gas to produce a temperature pulse.
C)excites a phosphor to produce a pulse of visible light.
D)hits a metal plate to produce a voltage pulse.
E)hits a metal plate, vaporizing atoms, to produce a pressure pulse.

Question 42

The half-life of a radioactive isotope is 1.0 minute. In an experiment, the number of decay events was monitored in 1-minute intervals over a 5-minute period. What would you predict for the most likely observations if 50 decay events were observed in the first minute? In the second minute, ________ events were observed, and in the last minute, ________ events were observed.

A)50; 50
B)25; 3
C)25; 25
D)50; 100
E)25; 13

Question 43

Common activity levels of radon-222 are in the range of 1 picocurie/liter (pCi/L) at room temperature and pressure. How many atoms of radon decay each minute in a 1 L sample of gas with radiation at this level? Recall that 1 Bq = 1 decay/s and 1 Ci = 3.7  10¹⁰ Bq.

A)6  10^4
B)6  10⁸
C)2  10¹²
D)2
E)4  10^2

Question 44

Plutonium-238 is an  emitter and a compact heat source. Coupled with a PbTe thermoelectric device, it was once used as a very reliable electrical energy source for cardiac pacemakers. What is the product of the radioactive decay of plutonium-238?

A)thorium-230
B)uranium-234
C)curium-242
D)californium-246
E)plutonium-234

Question 45

Tritium (³H) is used in glowing "EXIT" signs conveniently located where there is no electricity for lightbulbs. What decay route is likely for tritium?

A)( emission)
B)( emission)
C)positron emission
D)( emission)
E)X-ray emission

Question 46

Fluorine-18 is an isotope commonly used in radioimaging, due in part to the short half-life (~2 hours) of the isotope. What type of emission process is likely for fluorine-18?

A)( emission)
B)( emission)
C)positron emission
D)( emission)
E)X-ray emission

Question 47

A person's body generates about 0.2 Ci of radioactivity! Determine the total radioactivity emitted by 300 students in a lecture hall. (1 Ci = 3.7  10¹⁰ Bq and 1 Bq = 1 decay/s)

A)2  10⁶ decays/s
B)9  10¹⁶ decays/s
C)70 decays/s
D)2  10⁷ decays/s
E)7  10³ decays/s

Question 48

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Iodine-125, which decays by electron capture followed by gamma ray emission with a half-life of 59.4 days, is one isotope used for this treatment. If a tumor were seeded with 1.00 g of iodine-125 (124.90 g/mol), what would the initial radioactivity level be? Note: 1 Ci = 3.70  10¹⁰/s.

A)17.6 mCi
B)32.5 mCi
C)96.7 mCi
D)1.40 mCi
E)58.6 mCi

Question 49

Radon-222 has a half-life of 3.8 days. A sample from a basement in Colorado was analyzed 5.0 days after it was collected and found to have an activity of 0.17 Bq. What was the original activity of this sample?

A)0.22 Bq
B)0.32 Bq
C)0.42 Bq
D)0.62 Bq
E)0.52 Bq

Question 50

Polonium-210 is a radioactive isotope that was used as a fatal toxin in the poisoning of Alexander Litvinenko, a former KGB agent, in 2006. What type of emission process is likely for this isotope?

A)alpha
B)beta
C)positron
D)gamma ray
E)X-ray

Question 51

The activity of a radioactive sample is the number of decay events per second. The SI unit of activity is the becquerel (1 Bq = 1/s). An older unit for activity is the curie (1 Ci = 3.70  10¹⁰/s). What is the activity in Bq of a sample with an activity of 47  Ci of radiation?

A)7.9  10 ² Bq
B)7.9  10 ⁸ Bq
C)1.7  10¹² Bq
D)1.7  10 ⁶ Bq
E)1.3  10 ^16 Bq

Question 52

Which statement A-D, regarding the activity of a radioactive sample, is not correct?

A)The activity of a sample is the number of decay events per second.
B)The activity depends on a rate constant for the decay and the amount of the radioisotope in the sample.
C)Radioactive decay follows first-order reaction kinetics.
D)The activity will decrease to half its initial value in a time equal to ln(2)/k, where k is the rate constant.
E)A-D are all correct.

Question 53

The activity of a radioactive sample is the number of decay events per second. The SI unit of activity is the becquerel (1 Bq = 1/s). An older unit for activity is the curie (1 Ci = 3.70  10¹⁰/s). What is the activity in  Ci of a sample with an activity of 2.1 10 ⁵ Bq of radiation?

A)7.8  10 ⁹ Ci
B)5.7 Ci
C)5.7  10 ^12 Ci
D)5.7  10 ^6 Ci
E)0.21 Ci

Question 54

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Palladium-103, which decays by electron capture and gamma ray emission with a half-life of 17.0 days, is one isotope used for this treatment. How much palladium-103 (102.91 g/mol) is needed to produce an initial radioactivity level of 1.30 mCi? Note: 1 Ci = 3.70  10¹⁰/s.

A)0.0174 g
B)0.0251 g
C)0.0316 g
D)0.0995 g
E)0.0594 g

Question 55

When a positron and an electron collide, they ________

A)form a neutron.
B)strongly repel one another and recoil.
C)annihilate each other and produce gamma rays.
D)form a proton.
E)form a neutron and emit gamma rays.

Question 56

Strontium-90 is most likely to decay by ________

A)gamma emission.
B)beta emission.
C)positron emission.
D)alpha emission.
E)electron capture.

Question 57

Strontium-88 is the most abundant stable isotope. Strontium-90 is a particularly hazardous radioactive isotope because, as an alkali earth metal, it will substitute for calcium in bones and teeth. Predict its decay pathway.

A)( emission)
B)( emission)
C)positron emission
D)( emission)
E)X-ray emission

Question 58

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Cesium-131, which decays by electron capture and gamma ray emission with a half-life of 9.69 days, is a new isotope proposed for such treatment. If a tumor were seeded with 1.00 g of cesium-131 (130.91 g/mol), what would the initial radioactivity level be? Note: 1 Ci = 3.70  10¹⁰/s.

A)5.84 mCi
B)78.3 mCi
C)103 mCi
D)254 mCi
E)39.4 mCi

Question 59

Which of the following are devices that can be used to detect or measure radioactivity levels?

A)scintillation counters
B)chromatographs
C)Geiger counters
D)both A and C
E)both B and C

Question 60

Small traces of radioactive substances, mainly from the food we eat, are present in the human body. The most abundant radioisotope in the body is potassium-40. A person weighing 70 kg contains about 150 g of potassium, and about 0.01% of this amount is potassium-40. The half-life of potassium-40 is 1.25 10⁹ years. Estimate the rate at which radiation is produced by the decay of potassium-40 in the body.

A)4,000 decays/s
B)40,000 decays/s
C)400,000 decays/s
D)400 decays/s
E)4 decays/s

Question 61

A half-life is ________

A)the life that a nuclear chemist leads.
B)half of the lifetime of an unstable nucleus.
C)the time for one-half of the unstable nuclei to decay.
D)constantly changing.
E)independent of the rate constant for decay.

Question 62

What fraction of a sample's radioactive atoms remain after four half-lives?

A)
B)
C)
D)
E)

Question 63

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Palladium-103 is one isotope used for this treatment. Palladium-103 decays with a half-life of 17 days by emitting X-rays with a photon energy of 23,000 eV. What mass of palladium-103 would have to be embedded in a 25 g tumor to produce a radiation dose of 125 Gy in 2 months' time (60 days)? Note: 1 Gy = 1 J/kg, and 1 eV = 1.60  10^19 J.

A)0.37 g
B)0.31 g
C)0.10 g
D)0.23 g
E)0.16 g

Question 64

The activity of a sample of gas obtained from a basement containing radon-222 was found to be 8 pCi/L. This isotope has a half-life of 3.8 days. If no additional radon-222 entered the basement, how long would it take for the activity to decline to 1 pCi/L?

A)about 4 days
B)a bit more than 10 days
C)about 1 day
D)a bit less than 10 days
E)about 20 days

Question 65

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Iodine-125, with a half-life of 60 days, is one isotope used for this treatment. How long does it take for the activity of iodine-125 to decrease to 5.0% of its initial value?

A)4.44 days
B)17.57 days
C)221 days
D)259 days
E)354 days

Question 66

Uranium-238 ( ) decays to form thorium-234 ( ) with a half-life of 4.5  10 ⁹ years. How many years will it take for 75% of the uranium-238 to decay?

A)9.0  10 ¹⁰ years
B)4.5  10 ⁹ years
C)4.5  10 ¹⁰ years
D)9.0  10 ⁹ years
E)3.8  10 ⁹ years

Question 67

Which graph below describes the decay of two radioactive nuclides, P and Q, when the half-life of Q is longer than the half-life of P? In these graphs ln[N(0)/N(t)] is plotted on the y-axis, with time (t) on the x-axis. N(0) = number of radioactive nuclides present at time = 0, and N(t) = number present at time = t.

A)
B)
C)
D)

Question 68

Iodine-131 has a half-life of 8.1 days and is used as a tracer for the thyroid gland. If a patient drinks a sodium iodide (NaI) solution containing iodine-131 on a Tuesday, how many days will it take for the concentration of iodine-131 to drop to 5.0% of its initial concentration?

A)19 days
B)0.81 day
C)8.1 days
D)35 days
E)4.3 days

Question 69

The half-life for a radioactive sample ________

A)is independent of the rate constant for decay.
B)is directly related to the amount of radioactive sample.
C)is a larger value for a sample that decays quickly.
D)does not depend on the initial amount of sample present.
E)is the same for any isotope of a given radioactive element.

Question 70

Paxil (paroxetine) is a selective serotonin reuptake inhibitor (SSRI) used to treat depression. Its function in the brain can be studied by using radiolabeled ¹⁸F instead of natural abundance fluorine in its structure. The positron emission is detected by a PET scan. The half-life of ¹⁸F is 109.7 minutes. If radiolabeled Paxil were administered to a patient for a PET scan at 10:00 A.M. on a Wednesday, at what time would its activity reach 27% of the original activity?

A)10:50 A.M., Wednesday
B)7:27 P.M., Wednesday
C)3:12 A.M., Thursday
D)1:27 P.M., Wednesday
E)9:45 A.M., Thursday

Question 71

Tritium (³H) is used in glowing "EXIT" signs located where there is no electricity for lightbulbs. If the half-life of tritium is 12.26 years, what percentage of the original quantity of the isotope is left in the sign after 18.5 years?

A)0.632%
B)63.2%
C)35.1%
D)1.51%
E)25.0%

Question 72

A nerdy Scotch-drinking physicist, Nicola, suspected that the 50-year-old Scotch she purchased was misrepresented. Reasoning that water must contain the radioactive hydrogen isotope, tritium, because this isotope is produced in the atmosphere by cosmic rays, she decided she could use the tritium concentration in the Scotch to determine when it was bottled. She found that the tritium concentration in the Scotch was only 64% that of the tritium concentration in the water on the Isle of Islay where the Scotch was bottled. How old, really, was this 50-year-old Scotch? The half-life of tritium is 12.3 years.

A)6 years
B)8 years
C)12 years
D)24 years
E)It really was 50 years old.

Question 73

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Cesium-131 is a new isotope being proposed for this treatment. Cesium-131 decays with a half-life of 9.7 days by emitting X-rays with a photon energy of 29,000 eV. What mass of cesium-131 would have to be embedded in a 15 g tumor to produce a radiation dose of 115 Gy in 3 weeks' time (21 days)? Note: 1 Gy = 1 J/kg, and 1 eV = 1.60  10^19 J.

A)0.37 g
B)0.31 g
C)0.10 g
D)0.23 g
E)0.16 g

Question 74

Radioactive decay is a ________-order process.

A)Zero
B)First
C)Second
D)zero-or first
E)zero-first-or second

Question 75

Prozac (fluoxetine hydrochloride) is a selective serotonin reuptake inhibitor (SSRI) used to treat depression. Its function in the brain can be studied by using radiolabeled ¹⁸F instead of natural abundance fluorine in its structure. The positron emission is detected by a PET scan. The half-life of ¹⁸F is 109.7 minutes. If radiolabeled Prozac were administered to a patient for a PET scan at 8:00 A.M. on Monday, at what time would its activity reach 10% of the original activity?

A)9:49 A.M., Monday
B)9:07 P.M., Friday
C)10:42 A.M., Tuesday
D)2:04 P.M., Monday
E)6:07 P.M., Monday

Question 76

Fluorine-18 is a radioactive isotope used as a tracer atom in drugs in the human body. How much fluorine-18 was originally used in a drug sample if there is only 0.124 mg left in a sample after 2.5 h? (The half-life of fluorine-18 is 110 minutes.)

A)0.734 mg
B)1.00 mg
C)0.319 mg
D)0.578 mg
E)0.212 mg

Question 77

Which graph below describes the decay of two radioactive nuclides, P and Q, when the half-life of Q is shorter than the half-life of P? In these graphs ln[N(0)/N(t)] is plotted on the y-axis, with time (t) on the x-axis. N(0) = number of radioactive nuclides present at time = 0, and N(t) = number present at time = t.

A)
B)
C)
D)

Question 78

Phosphorus-32 is a radioactive isotope used as a tracer in the liver. How much phosphorus-32 was originally used if there is only 3.50 mg left in a sample after 288 h? (The half-life of phosphorus-32 is 14.3 days.)

A)1.96 mg
B)6.26 mg
C)4.17 mg
D)7.00 mg
E)17.9 mg

Question 79

How many half-lives did a radioactive sample complete if 2.5 g of a sample remains from 20 g of initial material?

A)One
B)Two
C)Three
D)four
E)five

Question 80

Radiation seed therapy is a common method for treating some prostate cancers and brain tumors. Palladium-103, with a half-life of 17 days, is one isotope used for this treatment. How long does it take for the activity of palladium-103 to decrease to 1.0% of its initial value and essentially cease to be effective?

A)3.7 mo
B)13 mo
C)2.1 mo
D)7.4 mo
E)4.2 mo