Question 1

The half-life of a radioactive substance is:

Accepted Answer

A)  half the time it takes for the entire substance to decay 
B)  usually about 50 years 
C)  the time for radium to change into lead 
D)  calculated from E = mc2 
E)  the time for half the substance to decay 
A)  half the time it takes for the entire substance to decay 
B)  usually about 50 years 
C)  the time for radium to change into lead 
D)  calculated from E = mc2 
E)  the time for half the substance to decay

Question 2

The relationship between the activity R, the disintegration constant λ, and the remaining number N of radioactive nuclei is:

Accepted Answer

A)  N = λR 
B)  R = λN 
C)  R = λ/N 
D)  R = N/ λ 
E)  R = λ ln N 
A)  N = λR 
B)  R = λN 
C)  R = λ/N 
D)  R = N/ λ 
E)  R = λ ln N

Question 3

The model of the nucleus in which each nucleon has its own well-defined quantum numbers is called the:

Accepted Answer

A)  collective model 
B)  quantum model 
C)  liquid drop model 
D)  independent model 
E)  atomic model 
A)  collective model 
B)  quantum model 
C)  liquid drop model 
D)  independent model 
E)  atomic model

Question 4

An alpha particle is:

Accepted Answer

A)  a helium atom with two electrons removed 
B)  an aggregate of two or more electrons 
C)  a hydrogen atom 
D)  the ultimate unit of positive charge 
E)  sometimes negatively charged 
A)  a helium atom with two electrons removed 
B)  an aggregate of two or more electrons 
C)  a hydrogen atom 
D)  the ultimate unit of positive charge 
E)  sometimes negatively charged

Question 5

The smallest particle of any chemical element that can exist by itself and yet retain the qualities that distinguish it as that element is:

Accepted Answer

A)  an electron 
B)  a proton 
C)  a neutron 
D)  an atom 
E)  a molecule 
A)  an electron 
B)  a proton 
C)  a neutron 
D)  an atom 
E)  a molecule

Question 6

Magnesium has atomic number 12, hydrogen has atomic number 1, and helium has atomic number 2. In the nuclear reaction 24Mg + 2H $\rightarrow$ ( ) + 4He the missing quantity is:

Accepted Answer

A)  23Na (Z = 11) 
B)  22Ne (Z = 10) 
C)  21Na (Z = 11) 
D)  21Ne (Z = 10) 
E)  22Na (Z = 11) 
A)  23Na (Z = 11) 
B)  22Ne (Z = 10) 
C)  21Na (Z = 11) 
D)  21Ne (Z = 10) 
E)  22Na (Z = 11)

Question 7

A certain nucleus, after absorbing a neutron, emits a $\beta$- and then splits into two alpha particles. The (A, Z) of the original nucleus must have been:

Accepted Answer

A)  6, 2 
B)  6, 3 
C)  7, 2 
D)  7, 3 
E)  8, 4 
A)  6, 2 
B)  6, 3 
C)  7, 2 
D)  7, 3 
E)  8, 4

Question 8

Which of the following nuclides is least stable?

Accepted Answer

A)  52Fe (Z = 26) 
B)  115Nd (Z = 60) 
C)  175Lu (Z = 71) 
D)  208Pb (Z = 82) 
E)  238U (Z = 92) 
A)  52Fe (Z = 26) 
B)  115Nd (Z = 60) 
C)  175Lu (Z = 71) 
D)  208Pb (Z = 82) 
E)  238U (Z = 92)

Question 9

Starting with a sample of pure 66Cu, 7/8 of it decays into Zn in 15 minutes. The corresponding half-life is:

Accepted Answer

A)  3.75 minutes 
B)  5 minutes 
C)  7 minutes 
D)  10 minutes 
E)  15 minutes 
A)  3.75 minutes 
B)  5 minutes 
C)  7 minutes 
D)  10 minutes 
E)  15 minutes

Question 10

A nucleus with mass number A and atomic number Z undergoes $\beta$- decay. The mass number and atomic number, respectively, of the daughter nucleus are:

Accepted Answer

A)  A, Z - 1 
B)  A - 1, Z 
C)  A + 1, Z - 1 
D)  A, Z + 1 
E)  A, Z 
A)  A, Z - 1 
B)  A - 1, Z 
C)  A + 1, Z - 1 
D)  A, Z + 1 
E)  A, Z

Question 11

The half-life of a radioactive isotope is 140 days. In how many days does the decay rate of a sample of this isotope decrease to one fourth its initial decay rate?

Accepted Answer

A)  35 days 
B)  70 days 
C)  105 days 
D)  210 days 
E)  280 days 
A)  35 days 
B)  70 days 
C)  105 days 
D)  210 days 
E)  280 days

Question 12

A radioactive atom X emits a $\beta$- particle. The resulting atom:

Accepted Answer

A)  must be very reactive chemically 
B)  has an atomic number that is one more than that of X 
C)  has a mass number that is one less than that of X 
D)  has an atomic number that is one less than that of X 
E)  is the same chemical element as X 
A)  must be very reactive chemically 
B)  has an atomic number that is one more than that of X 
C)  has a mass number that is one less than that of X 
D)  has an atomic number that is one less than that of X 
E)  is the same chemical element as X

Question 13

The half-life of a radioactive isotope is 6.5 h. If there are initially 48 * 1032 atoms of this isotope, the number of atoms of this isotope remaining after 26 h is:

Accepted Answer

A)  12 * 1032 
B)  6 * 1032 
C)  3 * 1032 
D)  6 *104 
E)  3 * 102 
A)  12 * 1032 
B)  6 * 1032 
C)  3 * 1032 
D)  6 *104 
E)  3 * 102

Question 14

In an alpha decay the disintegration energy appears as:

Accepted Answer

A)  photon energies 
B)  the kinetic energies of the alpha and the daughter nucleus 
C)  the excitation energy of the daughter nucleus 
D)  the excitation energy of the alpha particle 
E)  heat 
A)  photon energies 
B)  the kinetic energies of the alpha and the daughter nucleus 
C)  the excitation energy of the daughter nucleus 
D)  the excitation energy of the alpha particle 
E)  heat

Question 15

One curie is equivalent to:

Accepted Answer

A)  one Becquerel 
B)  one decay per second 
C)  3.0 x 108 decays per second 
D)  3.7 x 1010 decays per second 
E)  106 Becquerel 
A)  one Becquerel 
B)  one decay per second 
C)  3.0 x 108 decays per second 
D)  3.7 x 1010 decays per second 
E)  106 Becquerel

Question 16

Iron has atomic number 26. Naturally mined iron contains isotopes of mass numbers 54, 56, 57, and 58. Which of the following statements is FALSE?

Accepted Answer

A)  every atom of iron has 26 protons 
B)  some iron atoms have 30 neutrons 
C)  some iron atoms have 54 neutrons 
D)  the isotopes may be separated in a mass spectrometer 
E)  there are four kinds of naturally occurring iron atoms with the same chemical properties 
A)  every atom of iron has 26 protons 
B)  some iron atoms have 30 neutrons 
C)  some iron atoms have 54 neutrons 
D)  the isotopes may be separated in a mass spectrometer 
E)  there are four kinds of naturally occurring iron atoms with the same chemical properties

Question 17

A proton in a large nucleus:

Accepted Answer

A)  has a net attractive force on all other protons in the nucleus 
B)  has a net repulsive force on all other protons in the nucleus 
C)  has a net repulsive force on all other neutrons in the nucleus 
D)  has a net attractive force on some protons in the nucleus and a net repulsive force on others 
E)  has a net attractive force on some neutrons in the nucleus and a net repulsive force on others 
A)  has a net attractive force on all other protons in the nucleus 
B)  has a net repulsive force on all other protons in the nucleus 
C)  has a net repulsive force on all other neutrons in the nucleus 
D)  has a net attractive force on some protons in the nucleus and a net repulsive force on others 
E)  has a net attractive force on some neutrons in the nucleus and a net repulsive force on others

Question 18

Bromine, with atomic mass 79.942 u, is composed of nearly equal amounts of two isotopes, one of which contains 79 nucleons per atom. The mass number of the other isotope is:

Accepted Answer

A)  78 
B)  79 
C)  80 
D)  81 
E)  82 
A)  78 
B)  79 
C)  80 
D)  81 
E)  82

Question 19

Radioactive element A decays to the stable element B with a half-life T. Starting with a sample of pure A and no B, which graph below most correctly shows the number of A atoms, NA, as a function of time t?

Accepted Answer

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

Question 20

The 66Cu (Z = 29) produced in a nuclear bombardment is unstable, changing to 66Zn (Z = 30) by the emission of:

Accepted Answer

A)  a proton 
B)  a gamma ray photon 
C)  a positron 
D)  an electron 
E)  an alpha particle 
A)  a proton 
B)  a gamma ray photon 
C)  a positron 
D)  an electron 
E)  an alpha particle

Exam 42: Nuclear Physics

The half-life of a radioactive substance is:

The relationship between the activity R, the disintegration constant λ, and the remaining number N of radioactive nuclei is:

The model of the nucleus in which each nucleon has its own well-defined quantum numbers is called the:

An alpha particle is:

The smallest particle of any chemical element that can exist by itself and yet retain the qualities that distinguish it as that element is:

Magnesium has atomic number 12, hydrogen has atomic number 1, and helium has atomic number 2. In the nuclear reaction 24Mg + 2H →\rightarrow→ ( ) + 4He the missing quantity is:

A certain nucleus, after absorbing a neutron, emits a β\betaβ - and then splits into two alpha particles. The (A, Z) of the original nucleus must have been:

Which of the following nuclides is least stable?

Starting with a sample of pure 66Cu, 7/8 of it decays into Zn in 15 minutes. The corresponding half-life is:

A nucleus with mass number A and atomic number Z undergoes β\betaβ - decay. The mass number and atomic number, respectively, of the daughter nucleus are:

The half-life of a radioactive isotope is 140 days. In how many days does the decay rate of a sample of this isotope decrease to one fourth its initial decay rate?

A radioactive atom X emits a β\betaβ - particle. The resulting atom:

The half-life of a radioactive isotope is 6.5 h. If there are initially 48 * 1032 atoms of this isotope, the number of atoms of this isotope remaining after 26 h is:

In an alpha decay the disintegration energy appears as:

One curie is equivalent to:

Iron has atomic number 26. Naturally mined iron contains isotopes of mass numbers 54, 56, 57, and 58. Which of the following statements is FALSE?

A proton in a large nucleus:

Bromine, with atomic mass 79.942 u, is composed of nearly equal amounts of two isotopes, one of which contains 79 nucleons per atom. The mass number of the other isotope is:

Radioactive element A decays to the stable element B with a half-life T. Starting with a sample of pure A and no B, which graph below most correctly shows the number of A atoms, NA, as a function of time t?

The 66Cu (Z = 29) produced in a nuclear bombardment is unstable, changing to 66Zn (Z = 30) by the emission of:

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Filters

Magnesium has atomic number 12, hydrogen has atomic number 1, and helium has atomic number 2. In the nuclear reaction ²⁴Mg + ²H $\rightarrow$ ( ) + ⁴He the missing quantity is:

A certain nucleus, after absorbing a neutron, emits a $\beta$ ^- and then splits into two alpha particles. The (A, Z) of the original nucleus must have been:

Starting with a sample of pure ⁶⁶Cu, 7/8 of it decays into Zn in 15 minutes. The corresponding half-life is:

A nucleus with mass number A and atomic number Z undergoes $\beta$ ^- decay. The mass number and atomic number, respectively, of the daughter nucleus are:

A radioactive atom X emits a $\beta$ ^- particle. The resulting atom:

The half-life of a radioactive isotope is 6.5 h. If there are initially 48 * 10³² atoms of this isotope, the number of atoms of this isotope remaining after 26 h is:

Radioactive element A decays to the stable element B with a half-life T. Starting with a sample of pure A and no B, which graph below most correctly shows the number of A atoms, N_A, as a function of time t?

The ⁶⁶Cu (Z = 29) produced in a nuclear bombardment is unstable, changing to ⁶⁶Zn (Z = 30) by the emission of: