Deck 21: Nuclear Chemistry the Risks and Benefits

Question 1

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 alpha particles.

Answer 1

conversion of a proton to a neutron.

Question 2

Which one of the following statements is NOT correct?

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

Answer 2

Nucleons are held together in a nuclide by the electromagnetic force.

Question 3

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 alpha particles.

Answer 3

conversion of a neutron to a proton.

Question 4

Which of the following nuclides are most likely to be unstable because they have neutron-to-proton ratios greater than that predicted by the belt of stability?
I.carbon-14
II.sodium-26
III.sulfur-26
IV.aluminum-27
V.phosphorus-31

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

Question 5

All elements with Z $\gt$ 83 are

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

Question 6

High-energy radiation produced during nuclear change consists of

A)cosmic rays.
B)( $\gamma$ rays.)
C)gluons.
D)electrons.
E)positrons.

Question 7

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 $\gt$ 83 ultimately 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 generally increases.
E)It is very unusual to find a nuclide with an odd number of protons and an odd number of neutrons.

Question 8

For which of the following isotopes would it be unlikely to observe $\beta$ - decay?

A)²⁰F
B)¹³¹I
C)²⁷Mg
D)¹⁹O
E)¹³N

Question 9

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

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

Question 10

Which of the following statements regarding ordinary chemical reactions and nuclear reactions is correct?

A)The identity of an atom never changes during a nuclear reaction.
B)The identity of an atom may not change during an ordinary chemical reaction.
C)There can never be a change in the total mass measured before and after a chemical reaction or a nuclear reaction.
D)The energy change associated with a chemical reaction is always much greater than that of a nuclear reaction.
E)The free energy of the universe always increases during nuclear reactions.

Question 11

Electron-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 alpha particles.

Question 12

The first step in the disintegration of uranium-238 produces thorium-234.What particle is emitted in this reaction?

A)( $\alpha$ particle)
B)neutron
C)proton
D)( $\beta$ -particle)
E)( $\gamma$ ray)

Question 13

Cobalt-60 is a radioactive isotope of Co that is used for radiation therapy.It is originally produced from iron-58, which is first converted to Fe-59.Which particle did the Fe-58 absorb to become Fe-59?

A)( $\alpha$ particle)
B)electron
C)proton
D)neutron
E)( $\gamma$ ray)

Question 14

For which of the following isotopes would it be unlikely to observe electron capture?

A)²⁸Al
B)⁷Be
C)⁴⁹V
D)⁷³As
E)¹²⁵I

Question 15

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 16

The heaviest stable nucleus is an isotope of

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

Question 17

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

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

Question 18

Light elements with Z $\lt$ 20 generally have neutron-to-proton ratios about equal to

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

Question 19

The largest nuclear binding energy per nucleon occurs for an isotope of

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

Question 20

For which of the following isotopes would it be unlikely to observe $\beta$ - decay?

A)¹²⁰Te
B)⁹⁶Ru
C)¹⁰⁶Cd
D)¹¹⁸Sn
E)¹²⁴Xe

Question 21

Fluorine-18, which is often used in PET scans to locate tumors, decays to form a positron and oxygen-18.After 90.0 minutes, 1.00 18O is present relative to every 1.30 18F.Estimate the half-life of F-18.

A)288 minutes
B)109 minutes
C)156 minutes
D)175 minutes
E)238 minutes

Question 22

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

A)proton
B)neutron
C)( $\alpha$ )
D)positron
E)( $\alpha$ ).

Question 23

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 24

Uranium-238 decays to form thorium-234 with a half-life of 4.5 * 10⁹ years.How many years will it take for 75% of the uranium-238 to decay?

A)9.0 * 10⁹ years
B)4.5 * 10⁹ years
C)4.5 * 10¹⁰ years
D)9.0 *10¹⁰ years
E)3.8 * 10⁹ years

Question 25

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, 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 26

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 20.0 years?

A)0.677%
B)67.7%
C)32.3%
D)0.323%
E)25.0%

Question 27

Sodium-22 undergoes electron capture.Identify the resulting isotope.

A)magnesium-22
B)sodium-23
C)neon-22
D)magnesium-21
E)neon-21

Question 28

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 29

Suppose 62.0% of a sample of radioactive polonium-218 remains after 2.14 minutes.Estimate the half-life of Po-218.

A)3.10 minutes
B)1.19 minutes
C)6.20 minutes
D)1.40 minutes
E)3.40 minutes

Question 30

In 1913, an element was known to "emanate" from radium-226 by $\alpha$ emission and then to decay to polonium-218, also by $\alpha$ emission.What was the unknown element?

A)radon-222
B)lead-214
C)plutonium-238
D)bismuth-214
E)lead-218

Question 31

Radium-226 is formed as a product when which isotope undergoes $\beta$ + emission?

A)astatine-222
B)radon-226
C)francium-226
D)actinium-230
E)radium-225

Question 32

Phosphorus-32 is a radioactive isotope used in many biomedical applications.How much phosphorus-32 was originally used if there are 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 33

Suppose 67.5% of a sample of radioactive sodium-24 has decayed after one day.Estimate the half-life of Na-24.

A)3.89 days
B)3.24 days
C)14.8 hours
D)12.3 hours
E)1.79 days

Question 34

Phosphorus-32, a $\beta$ -emitter, is a radioactive isotope used in many biomedical applications.How much time has passed if the ratio of 32S to 32P is 4 to 5?( The half-life of phosphorus-32 is 14.3 days.)

A)11.4 days
B)16.7 days
C)4.60 days
D)12.1 days
E)16.9 days

Question 35

Which of the following statements regarding nuclear decay is NOT correct?

A)Radioactive decay is a random process.
B)All nuclei of a radionuclide decay at the same rate.
C)Nuclear decay always follows first-order kinetics.
D)A large number of nuclei is generally required to determine the half-life of a radionuclide.
E)In general, the more unstable the radionuclide, the shorter the half-life.

Question 36

Plutonium-238 is an $\alpha$ emitter.What is the product of the radioactive decay of Pu-238?

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

Question 37

A half-life is

A)the time required for all of a population to die.
B)half of the lifetime of an unstable nucleus.
C)the time required for one-half of a sample of an unstable nuclide to decay.
D)constantly changing.
E)independent of the rate constant for decay.

Question 38

Nitrogen-13 decays by positron emission to produce

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

Question 39

The half-life of chromium-51 is 27.8 days.How many half-lives have elapsed after one year?

A)2.32 t_½
B)32.4 t_½
C)1.08 t_½
D)13.1 t_½
E)0.0762 t_½

Question 40

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

A)( $\beta$ )
B)positron
C)neutron
D)( $\alpha$ )
E)( $\gamma$ )

Question 41

A 10.00 g sample of wood from an archaeological site produced 3072 $\beta$ - particles in a 10-hour measurement owing to the presence of carbon-14, while a 10.00 g sample of new wood produced 9216 $\beta$ - particles in the same period of time.The half-life of carbon-14 is 5730 years.How old is the wood from the archaeological site?

A)9080 years
B)2865 years
C)4040 years
D)5730 years
E)The correct answer differs by more than 100 years from any of the values given in A-D.

Question 42

The mass of a particular isotope is given by

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

Question 43

What quantity of energy would be produced when one gram of deuterium and one gram of tritium are allowed to completely react to form helium and a neutron? (1 kJ = 1000 kg m²/s²)

A)5.6 *10¹¹ J
B)1.7 * 10¹² J
C)2.8 * 10^-9 J
D)9.2 * 10¹³ J
E)3.1 * 10⁸ J

Question 44

What quantity of energy would be produced as one atom of plutonium-238 undergoes $\alpha$ decay to uranium-234? Round your answer to two significant figures.

A)6.0 *10^-7 J
B)2.6 *10^-8 J
C)7.0 * 10^-10 J
D)1.1 *10^-12 J
E)4.9 *10^-12 J

Question 45

What quantity of energy would be produced as 3.00 g of plutonium-238 undergoes $\alpha$ decay to uranium-234?

A)1.2 * 10¹⁰ J
B)2.7 * 10⁹
C)3.5 * 10⁸ J
D)3.6* 10¹⁰ J
E)6.2 *10^-13 J

Question 46

A barrel of oil produces about 5.9 *10⁶ kJ of energy.Fission of 235 g of uranium-235 releases 2.1 *10¹⁰ kJ of energy.How many barrels of oil are equivalent to 1.0 kg of uranium-235?

A)3600
B)15,000
C)840,000
D)110,000
E)55,000

Question 47

The argon-40 method of radioisotope dating was developed in the Geology Department at Stony Brook University to determine the age of rocks brought back from the moon.This method assumes that no ⁴⁰Ar gas was trapped when the molten rock solidified, and that no ⁴⁰Ar could escape from the solid rock.One sample that was analyzed had a ⁴⁰K to ⁴⁰Ar ratio of 0.100 N_K/N_Ar =0.100).⁴⁰K decays into ⁴⁰Ar by positron emission with a half-life of 1.28 = 109 years.How many years ago was this moon rock formed?

A)2.6*10⁸ years
B)2.3 *10⁹ years
C)4.4 * 10⁹ years
D)1.3 * 10¹⁰ years
E)1.3 *10⁸ years

Question 48

When bombarded by a proton, a lithium-7 nucleus reacts to form two $\alpha$ particles.How many kilojoules per gram of Li-7 are released during this nuclear transformation?( 1 kJ = 1000 kg m²/s²)

A)1.7 * 10⁹ kJ/g
B)3.9* 10⁴ kJ/g
C)5.6 F* 10^-9 kJ/g
D)7.9 * 10⁵ kJ/g
E)2.4 * 10⁸ kJ/g

Question 49

Carbon-14 measurements on the linen wrappings from the Book of Isaiah in the Dead Sea Scrolls indicated that the scrolls contained 79.5% of the carbon-14 found in living tissue.At the time they were analyzed, approximately how old were these scrolls? The half-life of carbon-14 is 5730 years.)

A)5.73 *10² years
B)8.20 *10² years
C)1.31 *10³ years
D)1.90 * 10³ years
E)4.56 *10³ years

Question 50

Which of the following statements regarding Einstein's equation relating mass and energy is correct?

A)Ordinary chemical change occurs too slowly for the conversion of mass to energy to be observed.
B)The amount of energy available from a nuclear reaction decreases as the change in mass increases.
C)Small changes in mass result in very large changes in energy because of the speed of light squared dependence.
D)The mass of the universe must remain constant even though energy is released during nuclear change.
E)The energy of the universe is decreasing because the mass of the universe is increasing.

Question 51

When carbon burns to produce carbon dioxide, 395 kJ/mol of energy is released.Approximately how much greater is the energy released per mole of deuterium in the following fusion process: 2 ²H $\rightarrow$ ⁴He? The atomic masses are 2.0141 g/mol for 2H and 4.0026 g/mol for 4He.(1 kJ = 1000 kg m²/s²)

A)102
B)104
C)106
D)108
E)1010

Question 52

What quantity of energy would be produced as 2.00 kg of plutonium-238 undergoes $\alpha$ decay to uranium-234? Round your answer to two significant figures.

A)2.4 * 10¹³ J
B)3.5* 10¹¹ J
C)6.2* 10^-10 J
D)1.2 * 10¹³ J
E)2.7 * 10¹² J

Question 53

When 4 protons and 4 neutrons combine to form a beryllium-8 nucleus, energy is released.Calculate the nuclear binding energy per nucleon.Here are some helpful data:

A)1.20 * 10^-6 J/nucleon
B)1.08 * 10^-9 J/nucleon
C)1.13 * 10^-12 J/nucleon
D)8.73 *10^-12 J/nucleon
E)1.08* 10^-15 J/nucleon

Question 54

What quantity of energy would be produced when one mole of deuterium reacts with one mole of tritium to form helium and a neutron? (1 kJ 1000 kg m²/s²)

A)1.7 * 10¹² J
B)5.6 *10⁶ J
C)2.8 * 10^-9 J
D)9.2 *10¹³ J
E)3.1 * 10⁸ J

Question 55

Compare the energy released by the collisions and annihilation of( 1) an electron and a positron and (2) a proton and an antiproton.

A)The energy released would be the same.
B)The energy released in (1) would be much greater than that released in (2).
C)The energy released in (2) would be much greater than that released in (1).
D)Energy is consumed in these processes, not released.
E)more energy is released in (2), because energy is not released in (1).

Question 56

A rock from the moon was found to contain 1.0 * 10^-5 g of uranium-238 and 4.0 * 10^-6 g lead-206.All of the lead-206 came from the decay of uranium-238.The half-life for this decay is 4.5 * 10⁹ years.How old is this rock?

A)1.0 * 10⁶ years
B)3.3 * 10⁷ years
C)4.1 *10⁸ years
D)2.5 * 10⁹ years
E)4.1 * 10¹⁰ years

Question 57

A Scotch-drinking physicist suspects that the 50-year-old Scotch s/he purchased was misrepresented.Reasoning that water must contain tritium because this isotope is produced in the atmosphere by cosmic rays, s/he uses the 3H concentration in the Scotch to determine when it was bottled.S/he finds that the 3H concentration in the Scotch was 64% that of the 3H concentration in the water on the Isle of Islay, where the Scotch was bottled.Approximately how old is 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 58

The method for determining the age of an object based on the quantity of a radionuclide or its decay products the object contains is

A)half-life analysis.
B)radionuclide tomography.
C)radiometric dating.
D)elemental analysis.
E)impossible.

Question 59

In 2002, a wooden beam from the Wupatki Indian ruin in Arizona was found to contain 235 mg of carbon-14.The same mass of wood from a tree -cut in 2002 contained 264 mg of carbon-14.When was the beam from Wupatki cut if the half-life of carbon-14 is 5730 years?

A)1969 AD
B)748 AD
C)962 AD
D)928 AD
E)1040 AD

Question 60

Plutonium-238, an $\alpha$ emitter and a compact heat source, has a half-life of 86 years.Coupled with a PbTe thermoelectric device, it is used as a very reliable electrical energy source for cardiac pacemakers.If 100.0 grams of 238Pu 238.0495 g/mol) were used in a pacemaker, how many $\alpha$ particles would it produce in 10 years?( 1 mole = 6.02 * 10²³ atoms)

A)6.02 * 10²³
B)3.01 * 10²³
C)3.01* 10²²
D)2.33 * 10²³
E)1.96 *10²²

Question 61

Hydrogen fusion always produces

A)an increase in mass number.
B)( $\beta$ particles.)
C)a new element.
D)an increase in the atomic number.
E)positrons.

Question 62

What other particle is formed during the fusion of two protons to form deuterium?

A)proton
B)neutron
C)electron
D)positron
E)( $\gamma$ ray)

Question 63

Which of the following statements regarding nuclear fission is NOT correct?

A)A larger nucleus generally splits into two smaller nuclei.
B)A radionuclide cannot undergo fission without being bombarded with neutrons.
C)Nuclear fission is often accompanied by the release of one or more neutrons and energy.
D)A chain reaction requires that at least one neutron from a fission event causes another nucleus to split apart.
E)Not all fissionable isotopes can sustain chain reactions.

Question 64

Extremely high temperatures are required to initiate nuclear fusion, but once initiated, energy is then released by nuclear fusion.This is analogous to

A)boiling a liquid by heating it.
B)melting a solid by heating it.
C)lighting a match to start a fire.
D)two magnets attracting each other.
E)coasting down a hill on your bicycle.

Question 65

Nuclear fusion produces energy because

A)neutrons are produced.
B)the total mass of the products is more than that of the reactants.
C)the total mass of the products is less than that of the reactants.
D)it is a very powerful chemical reaction.
E)photons are produced.

Question 66

The nucleus is held together by

A)the strong nuclear force.
B)the electromagnetic force.
C)the electroweak force.
D)Higgs bosons.
E)quarks.

Question 67

Why are higher temperatures necessary for fusion of helium nuclei than for hydrogen nuclei?

A)Helium is chemically inert.
B)Helium nuclei are heavier than hydrogen nuclei.
C)The boiling point of helium is higher than that of hydrogen.
D)Because E = mc² and helium nuclei are heavier than hydrogen nuclei.
E)The positive charges on helium nuclei are greater than those on the hydrogen nuclei.

Question 68

Which one of the following statements is NOT correct? A breeder reactor

A)converts plutonium-239 to fissionable uranium-235 through an $\alpha$ decay process.
B)converts unfissionable uranium-238 into fissionable plutonium-239.
C)produces more fuel than it consumes in producing energy.
D)is considered to be too hazardous for use in the United States.
E)All of these are correct.

Question 69

As the charges of identical small nuclei increase, the energy required to initiate nuclear fusion

A)decreases.
B)increases.
C)stays the same.
D)is proportional to their mass.
E)is inversely proportional to their mass.

Question 70

The natural abundance of uranium-235 is

A)a little less than 1%.
B)about 3-5%, depending on the source.
C)close to 100%.
D)0%; the isotope is made by transmutation.
E)approximately 40%.

Question 71

Uranium-235 is the fuel in nuclear power plants.When a nucleus of uranium-235 captures a neutron, the nucleus splits into two lighter nuclei and initiates a chain reaction.The chain reaction is driven by the emission of

A)protons.
B)neutrons.
C)positrons.
D)( $\beta$ particles.)
E)( $\alpha$ particles.)

Question 72

Which one of the following statements is NOT correct? A breeder reactor

A)converts uranium-238 into plutonium-239.
B)uses plutonium-239 as fuel.
C)produces more fuel than it uses.
D)produces plutonium-239 by $\beta$ emission from uranium-239.
E)All of these are correct.

Question 73

Which statement is NOT correct? During hydrogen fusion in our sun,

A)a neutron and a proton fuse together to form a deuteron.
B)two protons fuse together to form a deuteron and a positron.
C)a deuteron and a proton fuse to produce a helium-3 nuclide.
D)two helium-3 nuclides fuse to produce a helium-4 nuclide and two protons.
E)more stable nuclides are produced from less stable nuclides.

Question 74

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

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

Question 75

Nuclear fission produces energy because

A)neutrons are produced.
B)the total mass of the products is less than that of the reactants.
C)the total mass of the products is more than that of the reactants.
D)it is a very powerful chemical reaction.
E)photons are produced.

Question 76

Which of the following statements regarding uranium enrichment is NOT correct?

A)Extraction of uranium from its ore usually first produces an oxide called yellowcake.
B)Uranium oxides can be treated with hydrofluoric acid to make uranium hexafluoride.
C)235UF₆ is less dense than 238UF₆ and can be separated by centrifugation.
D)Different applications require different levels of uranium enrichment.
E)Uranium purified from its ore can be used directly in nuclear reactors but not in nuclear bombs.

Question 77

The difference between the uranium used in an atomic bomb and that used in a nuclear power plant is that

A)there is no difference.
B)the percentage of uranium-238 is much higher in the bomb.
C)the percentage of uranium-235 is much higher in the bomb.
D)the uranium in the bomb is 99.9% pure uranium.
E)the uranium in the bomb is mixed with plutonium.

Question 78

Suppose the reaction produces 1.664 *10¹⁰ kJ/mol of energy.
Calculate the change in mass in grams that occurs when one mole of U-235 reacts with one mole of neutrons.E = mc², where c = 2.998 *10⁸ m/s; 1 kg = 6.0221415 *10²⁶ amu; 1 J = 1kg · m²/s².

A)0.185 g
B)0.555 g
C)0.898 g
D)5.41 g
E)9.22 F*10^-17 g

Question 79

Which statement is NOT correct? During primordial nucleosynthesis,

A)neutrons and protons fused together to form deuterons.
B)deuterons fused together to form alpha particles.
C)more stable nuclides were formed from less stable nuclides.
D)gamma rays were produced.
E)colliding pairs of electrons annihilated each other.

Question 80

The quantity of material required to ensure that fission is self-sustaining is defined as

A)the critical mass.
B)the threshold mass.
C)one kilogram of a radionuclide.
D)the subcritical mass.
E)one mole of a radionuclide.