Fission & Fusion Quiz
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5 questions, one answer each
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1. What is nuclear fission?
- A. The joining of two small nuclei into a larger one
- B. The splitting of a large nucleus into two smaller daughter nuclei
- C. The decay of an unstable nucleus emitting an alpha particle
- D. The absorption of a proton by a nucleus
2. What is released, in addition to energy, when a U-235 nucleus undergoes fission after being struck by a neutron?
- A. Two radioactive daughter nuclei and a small number of neutrons
- B. One stable daughter nucleus only
- C. A proton and an electron
- D. Gamma rays only, with no nuclei produced
3. What is the function of control rods in a nuclear reactor?
- A. To slow down neutrons so they cause more fission
- B. To absorb neutrons and control the rate of the chain reaction
- C. To absorb radiation and protect workers
- D. To provide the initial neutrons to start fission
4. Why is nuclear fusion the energy source of stars but does not occur naturally on Earth at room temperature?
- A. Because Earth lacks hydrogen
- B. Because fusion requires extremely high temperature and pressure to overcome electrostatic repulsion between positive nuclei
- C. Because fusion only happens in a vacuum
- D. Because Earth's gravity is too strong
5. A reactor's moderator is removed by mistake while control rods remain fully inserted. What is the most likely immediate effect on the chain reaction?
- A. The reaction rate increases sharply because fewer neutrons are absorbed
- B. The reaction slows or stops, because fast neutrons are less likely to cause further fission in U-235 without being slowed down
- C. There is no effect, since the moderator only affects shielding
- D. The reactor core temperature drops to absolute zero