Chapter 34

1. Chapter 34 Nuclear Fission and Fusion

2. Nuclear fission was discovered and correctly identified by humans • shortly after the Italian Renaissance • at the turn of the 20th century. • near the middle of the 20th century. • at the close of the 20th century.

3. Nuclear fission was discovered and correctly identified by humans • shortly after the Italian Renaissance • at the turn of the 20th century. • near the middle of the 20th century. • at the close of the 20th century. Comment. Nuclear fission was discovered by Europeans in 1938.

4. The force that tends to push the atomic nucleus apart is • electrical. • nuclear. • chemical. • All of these.

5. The force that tends to push the atomic nucleus apart is • electrical. • nuclear. • chemical. • All of these.

6. The chain reaction that occurs in nuclear fission is a buildup of • energy. • electrons. • nucleons. • neutrons.

7. The chain reaction that occurs in nuclear fission is a buildup of • energy. • electrons. • nucleons. • neutrons.

8. The greater the surface area for a given mass of uranium, the • less likely a sustained chain reaction. • more likely a sustained chain reaction. • neither, for mass, rather than surface area, is significant. • None of these.

9. The greater the surface area for a given mass of uranium, the • less likely a sustained chain reaction. • more likely a sustained chain reaction. • neither, for mass, rather than surface area, is significant. • None of these. Explanation: When a chain reaction occurs, it fizzles out when neutrons escape a surface. So the greater the surface area, the less likely an explosion will occur.

10. A major problem in chemically separating uranium-235 from the more abundant uranium-238 stems from the fact that both • are isotopes of the same element. • have nearly the same mass. • have slightly different speeds. • are radioactive.

11. A major problem in chemically separating uranium-235 from the more abundant uranium-238 stems from the fact that both • are isotopes of the same element. • have nearly the same mass. • have slightly different speeds. • are radioactive. Comment: The chemical differences, not the physical ones, present the greatest problem in separating these isotopes from each other.

12. A nuclear fission reactor is • an elegant way to heat water. • unlike a fossil-fuel plant in every major way. • the only way known at present for getting energy from nothing. • a major polluter of the atmosphere.

13. A nuclear fission reactor is • an elegant way to heat water. • unlike a fossil-fuel plant in every major way. • the only way known at present for getting energy from nothing. • a major polluter of the atmosphere. Comment: Fossil-fuel plants are other ways of heating water.

14. Plutonium is an element that • fissions like uranium. • can be used in nuclear power plants. • ranks low as a cancer-producing substance. • All of these.

15. Plutonium is an element that • fissions like uranium. • can be used in nuclear power plants. • ranks low as a cancer-producing substance. • All of these.

16. A breeder reactor • converts uranium-238 into plutonium. • produces no greenhouse gases. • in time produces more fission fuel than it starts with. • All of these.

17. A breeder reactor • converts uranium-238 into plutonium. • produces no greenhouse gases. • in time produces more fission fuel than it starts with. • All of these.

18. A breeder reactor is a • fission device. • fusion device. • Both of these. • None of these.

19. A breeder reactor is a • fission device. • fusion device. • Both of these. • None of these.

20. Among lightweight hydrogen, middleweight iron, and heavyweight uranium, which of these three elements has the least mass per nucleon, that is, which effectively has the least massive nucleons in its nucleus? • Hydrogen • Iron • Uranium • Actually, the mass per nucleon is the same in each.

21. Among lightweight hydrogen, middleweight iron, and heavyweight uranium, which of these three elements has the least mass per nucleon, that is, which effectively has the least massive nucleons in its nucleus? • Hydrogen • Iron • Uranium • Actually, the mass per nucleon is the same in each. Comment: The graph of Figure 34.16, followed by those in Figures 34.17 and 34.19, says it all.

22. The apparent “name of the game” in power production for nucleons is to • lose mass. • gain mass. • keep a steady mass. • change mass to another form.

23. The apparent “name of the game” in power production for nucleons is to • lose mass. • gain mass. • keep a steady mass. • change mass to another form. Explanation: The loss in mass is met with an increase in energy.

24. When a sample of material undergoes fission, the total mass of the material after the event is • less. • the same. • more. • None of these.

25. When a sample of material undergoes fission, the total mass of the material after the event is • less. • the same. • more. • None of these. Explanation: Likewise for fusion. The name of the game for energy release is to lose mass. All reactions, nuclear or chemical, lose mass when energy release is the outcome.

26. In either a fission event or a fusion event, the quantity that remains unchanged is • energy. • the mass of nucleons. • the number of nucleons. • None of these.

27. In either a fission event or a fusion event, the quantity that remains unchanged is • energy. • the mass of nucleons. • the number of nucleons. • None of these. Explanation: This is a premise of reaction equations, whether nuclear or chemical. Although energy and mass themselves undergo changes, the number of particles and amount of charge remain unchanged. Count the particles in Figure 34.21.

28. To calculate the energy release of either a fission or a fusion reaction, first find the change in mass and • divide it by the speed of light squared. • multiply it by the speed of light squared. • square it, and multiply by the speed of light. • take its square root, then multiply by the speed of light squared.

29. To calculate the energy release of either a fission or a fusion reaction, first find the change in mass and • divide it by the speed of light squared. • multiply it by the speed of light squared. • square it, and multiply by the speed of light. • take its square root, then multiply by the speed of light squared. Explanation: This is letting the terms of the equation E = mc2 guide your thinking. Good physics!

30. Work is required to remove a nucleon from the atomic nucleus. When this occurs, the removed nucleon • loses some of its mass. • gains mass. • speeds up. • morphs to another nucleon.

31. Work is required to remove a nucleon from the atomic nucleus. When this occurs, the removed nucleon • loses some of its mass. • gains mass. • speeds up. • morphs to another nucleon.

32. In a mass spectrograph, the particles that sweep arcs of greatest radius by magnetic force are the particles that have • greatest mass. • greatest inertia • Both of these. • None of these.

33. In a mass spectrograph, the particles that sweep arcs of greatest radius by magnetic force are the particles that have • greatest mass. • greatest inertia • Both of these. • None of these. Explanation: Greatest mass and greatest inertia say much the same thing!

34. If an iron nucleus were to split in two, its fission fragments would have • more mass per nucleon. • less mass per nucleon. • the same mass per nucleon. • either more or less mass per nucleon.

35. If an iron nucleus were to split in two, its fission fragments would have • more mass per nucleon. • less mass per nucleon. • the same mass per nucleon. • either more or less mass per nucleon. Explanation: In this case, the products of the fission are higher on the “energy hill” and are more massive.