Q&A Hero

Q: Neutrons that will initiate the fission of U-235 require speeds that are A) less than average. B) about average. C) more than average. D) all of the above E) none of the above

Q: Two isotopes that undergo nuclear fission are A) U-235 and Pu-239. B) Th-238 and U-235. C) all of these D) none of these

Q: The water that operates a fission-reactor turbine is A) not the same water that flows through the reactor. B) heated to high-pressure steam. C) without radioactivity. D) all of the above E) none of the above

Q: The possible fate of a neutron in ordinary uranium metal is to A) cause fission of U-235 if present. B) escape the metal. C) be absorbed by U-238 without causing fission. D) all of the above E) none of the above

Q: Control is maintained in a nuclear reactor by control rods that A) absorb excess neutrons. B) emit fast neutrons. C) both of these D) neither of these

Q: The kinetic energy of fission fragments in a nuclear reactor A) superheats water and produces steam. B) converts to gamma-ray radiation. C) becomes radioactive pollution. D) converts directly to electricity. E) none of the above

Q: A nuclear power plant is very similar to A) nuclear bombs, but with more control. B) any conventional power plant, but with uranium as fuel. C) a photovoltaic solar cell power plant. D) all of the above E) none of the above

Q: Nuclear reactors that produce consumer power in present times are powered by A) fission. B) fusion. C) both fission and fusion.

Q: Which has the smaller critical mass; U-235 that releases 2.5 neutrons per fission, or Pu-239 that releases 2.7 neutrons per fission? A) U-235 B) Pu-239 C) both would have the same critical mass.

Q: In gaseous form at the same temperature, the average speed of U-238 compared to the speed of U-235 is A) less. B) more. C) the same.

Q: The idea in fission-bomb design is to A) form a supercritical mass from one or more subcritical masses. B) bring neutrons and subcritical uranium together. C) both of these D) neither of these

Q: When two pieces of fissionable material are assembled, the average distance that a neutron travels before escaping will A) decrease. B) increase. C) be the same.

Q: If a critical mass of fissionable material in a spherical shape is flattened like a hamburger, it will be A) supercritical. B) subcritical. C) as critical.

Q: The term critical mass refers to the least amount of mass that can A) sustain a chain reaction. B) squelch a chain reaction. C) explode when rapidly brought against a neighboring piece. D) none of the above

Q: A sphere of pure U-235 will explode if it is A) hot enough. B) shaken hard enough. C) big enough. D) none of the above

Q: Uranium-235, uranium-238 and uranium-239 are different A) elements. B) ions of the same element. C) isotopes of the same element. D) none of the above

Q: Compared with protons, neutrons are more effective nuclear bullets in nuclear reactions since they have A) slightly greater mass than a proton. B) no charge. C) a wider cross-section than a proton. D) all of the above E) none of the above

Q: A chain reaction progresses when the average number of liberated neutrons that cause further fissions is A) zero. B) less than one. C) one or more. D) none of the above

Q: In the fissioning of uranium, a chain reaction is caused by A) the kinetic energy of the decay products. B) ejected neutrons. C) alpha particles. D) none of the above

Q: Which will leak more neutrons? A) two separate lumps of uranium. B) the same two lumps stuck together. C) both the same

Q: When a lump of uranium is broken into smaller pieces, the total surface area A) decreases. B) remains the same. C) increases.

Q: Compared with the mass of a uranium nucleus before splitting, the split fragments have A) less mass. B) the same mass. C) more mass.

Q: The conversion of mass to energy of other forms via nuclear fission is A) less than 1%. B) about 10%. C) about 20%. D) about 30%. E) more than 30%.

Q: Electrical forces inside a nucleus contribute to nuclear A) stability. B) instability. C) both of these D) neither of these

Q: The balance between electrical and nuclear strong forces is more tenuous in A) light elements. B) middle size elements like iron. C) heavier elements. D) all of the above E) none of the above

Q: The fate of the world's uranium supply is to eventually become A) alpha and beta particles. B) iron. C) lead.

Q: Part of a wooden ancient ship is found to be 1/3 as radioactive as wood freshly cut from a tree. The age of the ship is likely about A) one-third of carbon-14's half-life. B) three times carbon-14's half-life. C) more than three times carbon-14's half-life. D) none of the above

Q: All deposits of natural uranium contain appreciable amounts of A) iron. B) lead. C) gold. D) all of the above E) none of the above

Q: Carbon dating requires that the object being tested contain A) organic material. B) inorganic material. C) charcoal. D) none of the above

Q: There is a greater proportion of carbon-14 in A) new bones. B) old bones. C) same in each

Q: Which of the following isotopes is radioactive? A) Carbon-12 B) Carbon-14 C) both of these D) neither of these

Q: Carbon-14 is produced in the atmosphere principally by A) plants and animals. B) cosmic-ray bombardment. C) nitrogen bombardment. D) photosynthesis. E) none of the above

Q: Free protons and neutrons are spewed throughout the atmosphere by A) nitrogen decay. B) carbon decay. C) the bombardment of cosmic rays upon atoms. D) all of the above E) none of the above

Q: The resulting atomic number of an element that emits 1 alpha particle, 1 positron, and 3 beta particles is A) decreased by 2. B) decreased by 1. C) unchanged. D) increased by 1. E) increased by 2.

Q: In order for an atom to decay to an element that is one greater in atomic number, it can emit A) one alpha particle and 3 beta particles. B) one positron and 2 beta particles. C) one beta particle. D) all of the above E) none of the above

Q: A hydrogen atom that emits an alpha particle is a routine occurrence in A) the environment. B) laboratories. C) unlikely. D) impossible.

Q: Artificially induced radioactive elements generally have A) long half-lives. B) short half-lives. C) no half-lives.

Q: In 1919 Rutherford performed the first historic artificial transmutations of A) hydrogen to helium. B) nitrogen to oxygen. C) carbon 12 to carbon 14. D) none of the above

Q: When the hydrogen isotope tritium-3 emits a beta particle, it becomes an isotope of A) hydrogen. B) helium. C) lithium. D) carbon. E) none of the above

Q: An element will decay to an element with higher atomic number in the periodic table if it emits A) a beta particle. B) a gamma ray. C) a proton. D) an alpha particle. E) none of the above

Q: When a nucleus emits a beta particle, its atomic number A) increases by 1. B) decreases by 1. C) increases by 2. D) decreases by 2. E) none of the above

Q: When a nucleus emits a positron, its atomic number A) increases by 1. B) decreases by 1. C) doesn't change.

Q: When thorium (A = 90) emits a beta particle, the resulting nucleus has atomic number A) 88. B) 89. C) 90. D) 92. E) none of the above

Q: When U-239 emits a beta particle, the resulting nucleus has A) 90 protons. B) 91 protons. C) 92 protons. D) 93 protons. E) 94 protons.

Q: When U-238 emits an alpha particle, the resulting nucleus has A) 90 protons. B) 91 protons. C) 92 protons. D) 93 protons. E) 94 protons.

Q: When radium (A = 88) emits an alpha particle, the resulting nucleus has atomic number A) 86. B) 88. C) 90. D) 92. E) none of the above

Q: When uranium emits an alpha particle, the result is A) thorium. B) protactinium. C) neptunium. D) none of the above

Q: When uranium emits a beta particle, the result is A) a uranium ion. B) a different isotope of uranium. C) the first transuranic element. D) all of the above E) none of the above

Q: In which of these processes is an element transformed into a completely different element? A) alpha decay B) beta decay C) both of these D) none of the above

Q: In a smoke detector americium (A = 95) transmutes to neptunium (A = 93) by A) beta emission. B) alpha emission. C) gamma emission. D) none of the above

Q: Radium (A = 88) transmutes to radon (A = 86) by A) beta emission. B) alpha emission. C) gamma emission. D) none of the above

Q: Pure elements can be transformed into entirely different elements by A) radioactive decay. B) transmutation. C) both of these D) neither of these

Q: When an element undergoes nuclear transmutation, the result is a completely different A) isotope of the same element. B) ion of the same element. C) element.

Q: Some charged particles in a bubble chamber are seen to move in spirals due to A) decreasing magnetic field. B) decreasing electric charge. C) perspective and parallax. D) energy dissipation.

Q: A device that shows the bending of particle trails in liquid hydrogen is a A) streamer chamber. B) spark chamber. C) bubble chamber. D) all of the above E) none of the above

Q: A magnetic field is applied to a cloud chamber for the purpose of A) attracting electrons. B) repelling electrons. C) attracting protons. D) all of the above E) none of the above

Q: A Geiger counter placed 1 meter from a point source of radiation registers 100 counts per minute. If the Geiger counter is moved closer, half-way to the source, the counting rate will be A) 25 counts/min. B) 50 counts/min. C) 100 counts/min. D) 200 counts/min. E) 400 counts/min.

Q: Which device is used primarily to detect nuclear radiation? A) synchrotron B) linear accelerator C) cyclotron D) scintillation counter E) none of the above

Q: The operation of a cloud chamber relies on A) magnetization. B) evaporation. C) acceleration. D) polarization. E) condensation.

Q: A certain radioactive isotope placed near a Geiger counter registers 120 counts per minute. If the half-life of the isotope is one day, what will be the count rate at the end of four days? A) 30 counts/min B) 15 counts/min C) 10 counts/min D) 7.5 counts/min E) 5 counts/min

Q: A certain radioactive isotope placed near a Geiger counter registers 160 counts per minute. Eight hours later, the counter registers 10 counts per minute. What is the half-life of the isotope? A) 8 hours B) 6 hours C) 4 hours D) 2 hours E) none of the above

Q: The half-life of carbon 14 is 5730 years. If a 1-gram sample of old carbon is 1/8 as radioactive as 1-gram of a current sample, then the age of the old sample is about A) 716 years. B) 11,500 years. C) 17,200 years. D) 22,900 years. E) 46,000 years.

Q: For 1 gram of radioactive material that has a half-life of one year, after 4 years the original radioactive material left will be A) 0 g. B) 1/2 g. C) 1/4 g. D) 1/8 g. E) none of the above

Q: For an isotope with a half-life of one day, at the end of three days the amount that remains is A) none. B) one-half. C) one-quarter. D) one-eighth. E) none of the above

Q: For an isotope with a half-life of one day, at the end of two days the amount that remains is A) none. B) one-half. C) one-quarter. D) one-eighth. E) none of the above

Q: The half-life of a radioactive substance is affected by A) pressure. B) temperature. C) age. D) all of the above E) none of the above

Q: The radioactive half-life of a material is the time for A) half of an original quantity of the material to decay. B) its decay rate to reduce to half. C) both of these D) neither of these

Q: Which nucleus has the greatest neutron/proton ratio? A) iron B) gold C) thorium D) uranium

Q: Nuclear stability is related to the balance between A) attracting and repelling forces in the nucleus. B) positive and negative ionic forces. C) both of these D) neither of these

Q: When the nucleus of an atom emits only a gamma ray, the atom's atomic number A) decreases. B) remains unchanged. C) increases.

Q: When the nucleus of an atom emits a beta particle, the atom's atomic number A) decreases. B) remains unchanged. C) increases.

Q: When the nucleus of an atom emits an alpha particle, the atom's atomic number A) decreases. B) remains unchanged. C) increases.

Q: A quark is a fundamental particle A) that makes up a nucleon. B) much smaller than a nucleon. C) not composed of smaller parts. D) all of the above E) none of the above

Q: Generally speaking, the larger a nucleus is, the greater its A) stability. B) instability. C) neither stability nor instability

Q: Once an alpha particle is outside the nucleus it is A) free to wander about the surrounding material. B) quickly bound to a neighboring nucleus. C) electrostatically repelled. D) radioactive.

Q: Electric forces within an atomic nucleus tend to A) hold it together. B) push it apart. C) neither of these

Q: Which is the strongest fundamental force? A) gravitational force. B) electric force. C) nuclear strong force. D) none of the above

Q: The mass of an atomic nucleon is nearly A) twice that of an electron. B) four times that of an electron. C) a thousand times that of an electron. D) two thousand times that of an electron.

Q: A nucleon is either a A) positron or an electron. B) proton or an electron. C) neutron or an electron. D) proton or a neutron.

Q: What must you do to get away from the harmful effects of radioactivity? A) live at the North or South Poles. B) go deep beneath Earth's surface. C) go to the Moon. D) die.