Question 1

Radioactive 90Sr has a half-life of 30 years.What percent of a sample of 90Sr will remain after 60 years?

Accepted Answer

A) 0% 
B) 14% 
C) 25% 
D) 50% 
E) 75% 
A) 0% 
B) 14% 
C) 25% 
D) 50% 
E) 75%

Question 2

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 3

Magic nucleon numbers are associated with:

Accepted Answer

A) nuclei that decay via alpha decay 
B) nuclei that decay via beta decay 
C) nuclei that have equal numbers of protons and neutrons 
D) nuclei that are relatively stable 
E) nuclei that fission readily 
A) nuclei that decay via alpha decay 
B) nuclei that decay via beta decay 
C) nuclei that have equal numbers of protons and neutrons 
D) nuclei that are relatively stable 
E) nuclei that fission readily

Question 4

Beta particles from various radioactive sources all have:

Accepted Answer

A) the same mass 
B) the same speed 
C) the same charge 
D) the same deflection 
E) the same energy in a magnetic field 
A) the same mass 
B) the same speed 
C) the same charge 
D) the same deflection 
E) the same energy in a magnetic field

Question 5

The energies of electrons emitted in $\beta$- decays have a continuous spectrum because:

Accepted Answer

A) the original neutron has a continuous spectrum 
B) the neutrino can carry off energy 
C) the emitted electron is free 
D) energy is not conserved 
E) the daughter nucleus may have any energy 
A) the original neutron has a continuous spectrum 
B) the neutrino can carry off energy 
C) the emitted electron is free 
D) energy is not conserved 
E) the daughter nucleus may have any energy

Question 6

Let Z denote the atomic number and A denote the mass number of a nucleus.The number of neutrons in this nucleus is:

Accepted Answer

A) Z 
B) A - Z 
C) A - 2Z 
D) A 
E) 2A - Z 
A) Z 
B) A - Z 
C) A - 2Z 
D) A 
E) 2A - Z

Question 7

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 8

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

Exam 42: Nuclear Physics

Radioactive 90Sr has a half-life of 30 years.What percent of a sample of 90Sr will remain after 60 years?

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?

Magic nucleon numbers are associated with:

Beta particles from various radioactive sources all have:

The energies of electrons emitted in β\betaβ - decays have a continuous spectrum because:

Let Z denote the atomic number and A denote the mass number of a nucleus.The number of neutrons in this nucleus is:

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?

One curie is equivalent to:

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Radioactive ⁹⁰Sr has a half-life of 30 years.What percent of a sample of ⁹⁰Sr will remain after 60 years?

The energies of electrons emitted in $\beta$ ^- decays have a continuous spectrum because: