Deck 19: Nuclear Chemistry

Question 1

Which of the following statements about electron capture is false?

A)The electron is used to convert a proton to a neutron.
B)The electron involved is most likely an outer shell valence electron.
C)In electron capture decay,the atomic number decreases by one.
D)In electron capture decay,the mass number remains unchanged.

Answer 1

The electron involved is most likely an outer shell valence electron.

Question 2

The number of nucleons in a U²⁺ nucleus is

A)92.
B)144.
C)236.
D)328.

Answer 2

236.

Question 3

Which of the following statements about positrons is false?

A)The positron has same mass as an electron.
B)A positron is ejected from the nucleus during the conversion of a proton into a neutron.
C)A positron is a positive electron.
D)When positron emission occurs,the atomic number of the nucleus increases.

Answer 3

When positron emission occurs,the atomic number of the nucleus increases.

Question 4

Positron emission changes the atomic number of an element by

A)-2.
B)-1.
C)+1.
D)+2.

Question 5

The nuclear decay process that involves the particle having the greatest mass is ________ emission.

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

Question 6

Which reaction below represents Th decay by alpha emission?

A)
Th →

He +

Ra
B)
Th →

He +

Ra
C)
Th →

P +

Ac
D)
Th →

N +

Th

Question 7

Which statement about nuclear reactions is true?

A)New elements are never produced in a nuclear reaction.
B)Nuclear reactions involve valence electrons.
C)The rate of a nuclear reaction is affected by catalysts.
D)Tremendous amounts of energy are involved in nuclear reactions.

Question 8

The number of nucleons in an atom or ion is the same as the

A)atomic number.
B)charge on the atom or ion.
C)mass number.
D)none of these

Question 9

In addition to a beta particle,what is the other product of beta decay of I?

A)
Sb
B)
Te
C)
Xe
D)
Cs

Question 10

A beta particle is

A)
E.
B)
E.
C)
P.
D)
He.

Question 11

The nuclear transformation potassium-40 argon-40 + ? is classified as

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

Question 12

Which reaction below represents Ti decay by electron capture?

A)
Ti +

E →

Ti
B)
Ti +

E →

Ti
C)
Ti +

E →

Ti
D)
Ti +

E →

Sc

Question 13

Tritium, H,is formed in the upper atmosphere when N captures a neutron and then decays.What is the other product of this reaction?

A)
C
B)
C
C)
B
D)
B

Question 14

Which of the following statements is not correct when balancing a nuclear equation? I.The mass numbers must be conserved on both sides of the reaction arrow.
II.The ionic charges must be conserved on both sides of the reaction arrow.
III.The atomic numbers must be conserved on both sides of the reaction arrow.
IV.The elements must be the same on both sides of the reaction arrow.

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

Question 15

Beta decay of ²⁴Na produces a beta particle and

A).²⁰F.
B).²³Na.
C).²⁴Ne.
D).²⁴Mg.

Question 16

An alpha particle is

A)
H⁺.
B)
H⁺.
C)
H⁺.
D)
He²⁺.

Question 17

Which of the following statements about gamma radiation is false?

A)It almost always accompanies alpha or beta emission.
B)It is a mechanism to release excess energy in the nucleus.
C)Gamma rays are high energy photons.
D)The mass number decreases by one with each gamma emitted.

Question 18

Which of the following decay processes give a product nuclide whose atomic number is one less than the starting nuclide?

A)alpha decay
B)beta decay and positron decay
C)gamma decay and beta decay
D)positron decay and electron capture

Question 19

Gamma radiation can be described as

A)a helium nucleus.
B)a negatively charged free electron.
C)high energy electromagnetic radiation.
D)a positively charged free electron.

Question 20

Which reaction below represents O decay by positron emission?

A)
O →

E +

Ra
B)
O →

E +

N
C)
O →

E +

O
D)
O →

E +

O

Question 21

A radioisotope which is neutron poor and very heavy is most likely to decay by

A)alpha emission,electron capture,or positron emission.
B)only alpha emission.
C)only electron capture.
D)only positron emission.

Question 22

Which process decreases the neutron/proton ratio?

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

Question 23

Fluorine-18 is a radioisotope widely used in positron emission tomography to investigate brain activity.The half-life is 109.8 minutes.How long will it take for 2.75 μg of ¹⁸F to decay to 500 ng?

A)0.288 min
B)270 min
C)871 min
D)2.06 × 10³ min

Question 24

Neptunium-239 has a half-life of 2.35 days.How many days must elapse for a sample of ²³⁹Np to decay to 1.00% of its original quantity?

A)0.0640 days
B)0.736 days
C)1.36 days
D)15.6 days

Question 25

If a sample of ²³³Pa takes 62.7 days to decrease to 20.0% of its original mass,what is its half-life?

A)0.0370 days
B)27.0 days
C)157 days
D)195 days

Question 26

Which of the following processes will decrease the neutron/ proton ratio?

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

Question 27

What is the decay constant for a radioactive isotope which decreases to 34% of its original value in 2.48 hours?

A)0.137 hr^-1
B)0.168 hr^-1
C)0.435 hr^-1
D)2.30 hr^-1

Question 28

As the atomic number of the elements increases,the ratio of neutrons to protons in stable nuclei

A)decreases.
B)stays the same.
C)increases.
D)is unrelated to stability.

Question 29

A radioisotope has a neutron/proton ratio which is too low.Which of the following processes will not occur for such a nucleus?

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

Question 30

Iodine-123,used in thyroid therapy,has a half-life of 13.27 hours.How many half-lives are required for a 160 mg sample of iodine-123 to decay to 5.0 mg?

A)0.031
B)1.0
C)5.0
D)32

Question 31

An experiment with ⁵⁵Co takes 47.5 hours.At the end of the experiment,1.90 ng of ⁵⁵Co remains.If the half life is 18.0 hours,how many ng of ⁵⁵Co were originally present?

A)2.47 ng
B)3.05 ng
C)3.28 ng
D)11.8 ng

Question 32

A researcher needs 5.00 mg of ¹²⁸Ba for an experiment.If the half-life of ¹²⁸Ba is 2.43 days,how many milligrams of ¹²⁸BaCl₂ must she order from the manufacturer if it takes 4.50 days to ship the material from the manufacturer to the university? (Assume the molar mass of ¹²⁸Ba is 128 g/mol. )

A)11.6 mg
B)18.0 mg
C)21.5 mg
D)44.9 mg

Question 33

What percentage of a radioactive substance remains after 6.00 half-lives have elapsed?

A)0.78%
B)1.56%
C)3.31%
D)6.25%

Question 34

Which of the following elements would be expected to be particularly stable?

A)
Ca
B)
K
C)
Ar
D)
Cl

Question 35

Which of the following elements would you expect to have the largest number of stable isotopes? Element number:

A)48
B)49
C)50
D)51

Question 36

Mass defect is the mass lost when

A)an atom is formed from individual protons,neutrons,and electrons.
B)a nucleus is formed from individual protons and neutrons.
C)electrons are removed from an atom.
D)electrons are added to an atom.

Question 37

Which one of the following statements about isotopes is false?

A)The ratio of neutrons to protons is about 1:1 for elements lighter than Ca.
B)The ratio of neutrons to protons is > 1:1 for elements heavier than Ca.
C)Nonradioactive isotopes generally have an odd number of neutrons.
D)All isotopes beyond ²⁰⁹Bi are radioactive.

Question 38

Which of the following statements regarding nuclear stability is true?

A)A stable element always has an equal number of protons and neutrons.
B)The most abundant isotope of an element always has an equal number of protons and neutrons.
C)Very few elements have at least one radioactive isotope.
D)Hydrogen is the only element whose most abundant isotope contains more protons than neutrons.

Question 39

Fluorine-18 is an isotope used in Positron Emission Tomography (PET)to scan the brain.If a researcher has 1.50 μg of ¹⁸F,how long before it decays to 1.0 ng? The half-life of ¹⁸F is 109.8 minutes.

A)5.2 × 10^-2 hr
B)4.6 × 10^-2 hr
C)19 hr
D)51 hr

Question 40

Which one of the following combinations of neutrons/protons results in the lowest number of nonradioactive (stable)isotopes?

A)even number protons/even number neutrons
B)even number protons/odd number neutrons
C)odd number protons/even number neutrons
D)odd number protons/odd number neutrons

Question 41

In fusion reactions to make superheavy elements,energy is required to bring the two nuclei together and to form additional mass.How much energy must be converted into mass for the alpha bombardment of ²⁵³Es to form ²⁵⁷Md? (The isotopic masses are ²⁵³Es = 253.08294 amu,⁴He = 4.00260 amu,²⁵⁷Md = 257.09558 amu. )

A)3.01 × 10⁶ kJ/mol
B)9.04 × 10⁸ kJ/mol
C)3.59 × 10¹¹ kJ/mol
D)7.21 × 10¹¹ kJ/mol

Question 42

The total binding energies for ³He,⁴He,and ⁶He are 7.72 MeV,28.29 MeV,and 29.26 MeV respectively.Arrange the 3 isotopes in increasing order of binding energy per nucleon.

A).³He < ⁴He < ⁶He
B).⁶He < ⁴He < ³He
C).⁴He < ³He < ⁶He
D).³He < ⁶He < ⁴He

Question 43

Which reaction is expected to release the greatest amount of energy?

A)2 H → H₂
B)
H +

H →

He
C)
N +

U →

Te +

Zr + 2 ¹n
D)
N +

U →

Ba +

Kr + 3

N

Question 44

Choose the words that best complete the following sentence. The ________ the binding energy,the ________ stable the nucleus.

A)larger,less
B)larger,more
C)smaller,less
D)smaller,more

Question 45

A binding energy curve is a plot of binding energy per nucleon versus atomic number.In what region of the binding energy curve are the most stable elements found?

A)in the lower left region (low atomic mass)
B)in the central top region (moderate atomic mass)
C)in the lower right region (heavy atomic mass)
D)binding energy is not dependent on atomic mass

Question 46

Four heavy elements (A, B, C, and D) will fission when bombarded by neutrons. In addition to fissioning into two smaller elements, A also gives off a beta particle, B gives off gamma rays, C gives off neutrons, and D gives off alpha particles. Which element would make a possible fuel for a nuclear reactor?

A)element A
B)element B
C)element C
D)element D

Question 47

Nitrogen-14 (14.003074 amu)is synthesized in the sun by fusion of ¹³C (13.003355 amu)and ¹H (1.007825 amu).How much energy is released in this nuclear reaction?

A)2.432 × 10⁶ kJ/mol
B)7.295 × 10⁸ kJ/mol
C)9.141 × 10¹⁰ kJ/mol
D)1.807 × 10¹¹ kJ/mol

Question 48

The binding energy is defined as

A)the amount of energy absorbed when electrons are added to an ion.
B)the amount of energy absorbed when protons and neutrons form a nucleus.
C)the amount of energy released when electrons are removed from the atom.
D)the amount of energy required to break apart a nucleus into individual protons and neutrons.

Question 49

Elements with ________ atomic mass are best possible candidates for a fission reaction.

A)very low
B)moderate
C)moderate to heavy
D)very heavy

Question 50

Breaking a chemical bond requires approximately 10² kJ/mol of energy.What is closest to the order of magnitude of the energy required to split a nucleus in to its individual protons and neutrons?

A)10³ kJ/mol
B)10⁴ kJ/mol
C)10⁸ kJ/mol
D)10¹⁰ kJ/mol

Question 51

If the mass of one neutron is 1.00866 amu,the mass of one proton is 1.00728 amu,and the mass of ¹²C nucleus is 11.99671 amu,calculate the binding energy for the ¹²C nucleus.

A)8.90 × 10⁹ kJ/mol
B)8.90 × 10¹² kJ/mol
C)1.10 × 10¹⁵ kJ/mol
D)1.10 × 10¹⁸ kJ/mol

Question 52

If the mass of one neutron is 1.00866 amu,the mass of one proton is 1.00728 amu,and the mass of ¹⁴C nucleus is 13.99995 amu,calculate the binding energy for the ¹⁴C nucleus.

A)9.92 × 10⁹ kJ/mol
B)1.02 × 10¹⁰ kJ/mol
C)5.54 × 10¹¹ kJ/mol
D)5.95 × 10¹¹ kJ/mol

Question 53

The sum of the masses of the protons and neutrons in a given nucleus minus the mass of that nucleus is always

A)negative.
B)positive.
C)temperature dependent.
D)zero.

Question 54

How much energy is released for alpha decay of ²³⁶U? The masses of ⁴He,²³²Th,and ²³⁶U are 4.002604,232.038124,and 236.045637 amu,respectively.

A)1.473 × 10⁸ kJ/mol
B)4.418 × 10⁸ kJ/mol
C)4.909 × 10⁸ kJ/mol
D)7.209 × 10⁸ kJ/mol

Question 55

Calculate the mass defect for the formation of phosphorus-31.The mass of a phosphorus-31 nucleus is 30.973765 amu.The masses of a proton and a neutron are 1.00728 and 1.00866 amu,respectively.

A)0.13015 amu
B)0.15404 amu
C)0.27261 amu
D)0.27399 amu

Question 56

Which does not apply to a nuclear fusion reaction?

A)Atoms of one element cannot be converted to atoms of another element.
B)Energy is conserved.
C)Matter is conserved.
D)None of these apply to a nuclear fusion reaction.

Question 57

Elements with ________ atomic mass are best possible candidates for a fusion reaction.

A)very low
B)moderate
C)moderate to heavy
D)very heavy

Question 58

What is the mass change in grams for the reaction 2 NO₂(g)→ N₂O₄(g)? The enthalpy for the reaction is -57.2 kJ.

A)-6.36 × 10^-13 g
B)-6.36 × 10^-10 g
C)-1.91 × 10^-7 g
D)-1.91 × 10^-4 g

Question 59

Which of the following is not an advantage of fusion reactions over fission reactions for power generation?

A)cheap and plentiful fuel
B)ease of reaction initiation
C)Fusion products are non-polluting.
D)Fusion products are nonradioactive.

Question 60

What does the term "critical mass" mean? It is the

A)amount of fissionable material which will self-sustain a nuclear chain reaction.
B)difference between mass of individual protons and neutrons and the mass of the nucleus.
C)energy which holds the nucleus together.
D)mass of fuel in a nuclear reactor core.

Question 61

Which unit of radiation describes the amount of energy absorbed by a kilogram of tissue exposed to a radiation source?

A)becquerel
B)curie
C)rad
D)rem

Question 62

The first transuranium element was synthesized by bombarding U with neutrons.After capturing one neutron,the resulting nuclide was unstable and decayed by beta emission.What was the product of these two nuclear reactions?

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

Question 63

The effects of ionizing radiation depend on

A)length of exposure to radiation.
B)location of source (internal or external).
C)type and energy of radiation.
D)All of these

Question 64

A shorthand way of writing transmutation equations is to show the bombarding particle and the subsequent emitted particle in parentheses.Which of the following equations shows the balanced nuclear reaction for Li (n,α)?

A)
Li +

N →

He +

H
B)
Li +

He →

N +

B
C)
Li +

N →

He +

He
D)
Li +

He →

N +

Be

Question 65

Which one of the following is most penetrating?

A)alpha particles
B)beta particles
C)gamma rays
D)positrons

Question 66

Which unit of radiation describes the amount of radiation emitted by a radioactive substance?

A)becquerel
B)gray
C)rad
D)rem

Question 67

Radiation is detected by its ________ properties.

A)gravitational
B)ionizing
C)kinetic
D)thermal

Question 68

A becquerel is

A)the amount of sample that undergoes 1 disintegration per second.
B)the amount of sample that undergoes 3.7 × 10¹⁰ disintegrations per second.
C)the amount of tissue damage done by radiation.
D)equal to 0.01 J of energy absorbed per kilogram of tissue.

Question 69

A sievert is

A)the amount of sample that undergoes 1 disintegration per second.
B)the amount of sample that undergoes 3.7 × 10¹⁰ disintegrations per second.
C)the amount of tissue damage done by radiation.
D)equal to 0.01 J of energy absorbed per kilogram of tissue.

Question 70

A curie is

A)the amount of sample that undergoes 1 disintegration per second.
B)the amount of sample that undergoes 3.7 × 10¹⁰ disintegrations per second.
C)the amount of tissue damage done by radiation.
D)equal to 0.01 J of energy absorbed per kilogram of tissue.

Question 71

Ionizing radiation having the lowest energy is exhibited by

A)α particles.
B)β particles.
C)γ rays.
D)X-rays.

Question 72

Which unit of radiation is frequently used in medicine to describe the amount of tissue damage caused by a radioactive substance?

A)becquerel
B)curie
C)rad
D)rem

Question 73

Which one of the following instruments would be the least suitable for detecting particles given off in radioactive decay?

A)electron microsope
B)Geiger counter
C)photographic film
D)scintillation counter

Question 74

An element, X is formed by bombardment of uranium-238 atoms with a beta particle.How many neutrons are produced by this reaction?

A)3
B)2
C)1
D)0

Question 75

A shorthand way of writing transmutation equations is to show the bombarding particle and the subsequent emitted particle in parentheses.Which particle is produced by Li (p,α)?

A)
H
B)
He
C)
Be
D)
He

Question 76

The masses of ⁴He,⁶Li,and ¹⁰B are 4.0015,6.0135,and 10.0102 amu respectively.The fission of a boron-10 nucleus into He-4 and Li-6 would

A)absorb energy.
B)evolve energy.
C)result in no energy change.
D)Need more information

Question 77

Oxygen-16 (15.994915 amu)is synthesized in the sun by fusion of ¹²C (12.000000 amu)and ⁴He (4.00260 amu).How much energy is released in this nuclear reaction?

A)2.48 × 10³ kJ/mol
B)2.30 × 10⁶ kJ/mol
C)6.92 × 10⁸ kJ/mol
D)7.20 × 10¹¹ kJ/mol

Question 78

A rad is

A)the amount of sample that undergoes 1 disintegration per second.
B)the amount of sample that undergoes 3.7 × 10¹⁰ disintegrations per second.
C)the amount of tissue damage done by radiation.
D)equal to 0.01 J of energy absorbed per kilogram of tissue.

Question 79

What is the missing product of the nuclear reaction? Bi + p → ? + Po

A)α
B)β+
C)β-
D)n

Question 80

Which ionizing radiation has the greatest energy?

A)α
B)β
C)γ
D)χ