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Nuclear Chemistry

Examples of
Multiple Choice Questions

The "magic numbers" for atoms are
(a) numbers of electrons that confer atomic stability.
(b) numbers of protons and/or neutrons that confer nuclear stability.
(c) n/p ratios that confer nuclear stability.
(d) atomic masses that confer nuclear stability.
(e) atomic masses that indicate fissile isotopes.

The actual mass of a 37Cl atom is 36.966 amu. Calculate the mass defect (amu/atom) for a 37Cl atom.
(a) 0.623 amu
(b) 0.388 amu
(c) 0.263 amu
(d) 0.341 amu
(e) none of these

The mass defect for an isotope was found to be 0.410 amu/atom. Calculate the binding energy in kJ/mol of atoms. (1 J = 1 kgm2/s2)
(a) 3.69 x 1010 kJ/mol
(b) 1.23 x 1020 kJ/mol
(c) 3.69 x 1013 kJ/mol
(d) 1.23 x 103 kJ/mol
(e) 1.23 x 1023 kJ/mol

Calculate the binding energy per nucleon (in units of MeV) for 9Be, for which the atomic mass is 9.01219 amu. Particle masses in amu are: proton = 1.007277; neutron = 1.008665; electron = 0.0005486. Conversion factor for E = mc2 is 931 MeV/amu.
(a) 6.46 MeV
(b) 6.33 MeV
(c) 6.23 MeV
(d) 11.39 MeV
(e) 56.93 MeV

Which isotope below has the highest nuclear binding energy per gram? No calculation is necessary.
(a) 4He
(b) 16O
(c) 32S
(d) 55Mn
(e) 238U

Which of the following statements is incorrect?
(a) Mass defect is the amount of matter that would be converted into energy if a nucleus were formed from initially separated protons and neutrons.
(b) Nuclear binding energy is the energy released in the formation of an atom from subatomic particles.
(c) Nuclei with highest binding energies are the most stable nuclei.
(d) Einstein postulated the Theory of Relativity in which he stated that matter and energy are equivalent.
(e) Mass number is the sum of all protons and electrons in an atom.

A positron has a mass number of _____, a charge of _____, and a mass equal to that of a(an) _____.
(a) 0, 1+, proton
(b) 1, 2+, proton
(c) 0, 1+, electron
(d) 1, 2+, electron
(e) 0, 0, proton

Emission of which one of the following leaves both atomic number and mass number unchanged?
(a) positron
(b) neutron
(c) alpha particle
(d) gamma radiation
(e) beta particle

Which type of radiation is the least penetrating?
(a) alpha
(b) beta
(c) gamma
(d) x-ray
(e) neutron

A radioisotope of argon, 35Ar, lies below the "band of stability: (n/p ratio too low). One would predict that it decays via _____.
(a) neutron emission
(b) beta emission
(c) positron emission
(d) alpha emission
(e) fission

A Geiger-Muller tube is a _____ .
(a) gas ionization detector
(b) cloud chamber
(c) fluorescence detector
(d) spectrophotometer
(e) photographic detector

The half life of 231Pa is 3.25 x 104 years. How much of an initial 10.40 microgram sample remains after 3.25 x 105 years?
(a) 0.0102 micrograms
(b) 0.240 micrograms
(c) 2.18 micrograms
(d) 0.0240 micrograms
(e) 1.04 micrograms

Consider the case of a radioactive element X which decays by electron (beta) emission with a half-life of 4 days to a stable nuclide of element Z. Which of the following statements is CORRECT?
(a) After 8 days the sample will consist of one-fourth element Z and three-fourths element X.
(b) Element Z will weigh exactly the same as element X when decay is complete (weighed to an infinite number of significant figures).
(c) 2.0 g of element X is required to produce 1.5 g of element Z after 8 days (to 2 significant figures).
(d) If element X as an atomic number equal to n, then element X has an atomic number equal to n-1.
(e) None of the above.

Carbon-11 is a radioactive isotope of carbon. Its half-life is 20 minutes. What fraction of the initial number of C-11 atoms in a sample will have decayed away after 80 minutes?
(a) 1/16
(b) 1/8
(c) 1/4
(d) 7/8
(e) 15/16

How old is a bottle of wine if the tritium (3H) content (called activity) is 25% that of a new wine? The half-life of tritium is 12.5 years.
(a) 1/4 yr
(b) 3.1 yr
(c) 25 yr
(d) 37.5 yr
(e) 50 yr

A Geiger counter registered 1000 counts/second from a sample that contained a radioactive isotope of polonium. After 5.0 minutes, the counter registered 281 counts/second. What is the half-life of this isotope in seconds?
(a) 87
(b) 110
(c) 164
(d) 264
(e) 2.18

The 14C activity of some ancient Peruvian corn was found to be 10 disintegrations per minute per gram of C. If present-day plant life shows 15 dpm/g, how old is the Peruvian corn? The half-life of 14C is 5730 years.
(a) 1455 years
(b) 1910 years
(c) 3350 years
(d) 3820 years
(e) 9080 years

Which of the following describes what occurs in the fission process?
(a) A heavy nucleus is fragmented into lighter ones.
(b) A neutron is split into a neutron and proton.
(c) Two light nuclei are combined into a heavier one.
(d) A proton is split into three quarks.
(e) A particle and anti-particle appear in an area of high energy density.

Which of the following statements about nuclear fission is always correct?
(a) Very little energy is released in fission processes.
(b) Nuclear fission is an energetically favorable process for heavy atoms.
(c) Due to its instability, 56Fe readily undergoes fission.
(d) In fission reactions, a neutron is split into a proton and an electron.
(e) All nuclear fission reactions are spontaneous.

Which one of the following would be most likely to undergo thermonuclear fusion?
(a) 2H
(b) 4He
(c) 56Fe
(d) 141Ba
(e) 235U

Which one of the following statements about nuclear reactions is false?
(a) Particles within the nucleus are involved.
(b) No new elements can be produced.
(c) Rate of reaction is independent of the presence of a catalyst.
(d) Rate of reaction is independent of temperature.
(e) They are often accompanied by the release of enormous amounts of energy.

Complete and balance the following equation. The missing term is _____ .
239Pu + alpha particle _____ + neutron
(a) 2 115Ag
(b) 2 106Rh
(c) 235U
(d) 233Pa
(e) 242Cm

When 59Cu undergoes positron emission, what is the immediate nuclear product?
(a) 59Ni
(b) 58Ni
(c) 58Cu
(d) 59Zn
(e) 58Zn

As a result of the process of electron capture ("K-capture") by 211At, the new isotope formed is:
(a) 210At
(b) 212At
(c) 211Po
(d) 211Rn
(e) 207Bi

When 235U is bombarded with one neutron, fission occurs and the products are three neutrons, 94Kr, and _____ .
(a) 139Ba
(b) 141Ba
(c) 139Ce
(d) 139Xe
(e) 142I


1. (b) 2. (d) 3. (a) 4. (a) 5. (d) 6. (e) 7. (c) 8. (d) 9. (a) 10. (c) 11. (a) 12. (a) 13. (c) 14. (e) 15. (c) 16. (c) 17. (c) 18. (a) 19. (b) 20. (a) 21. (b) 22. (e) 23. (a) 24. (c) 25. (a)

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To report any corrections, please e-mail Dr. Wendy Keeney-Kennicutt.