Fusion Knowledge-Based Practice

Questions

1. 1.

   In the proton-proton chain reaction, which serves as the primary fusion mechanism in stars with masses comparable to the Sun, what is the overall net nuclear transformation?

   • A) Three helium-4 nuclei fuse to produce one carbon-12 nucleus and gamma radiation.
   • B) Two deuterium nuclei fuse to produce one helium-3 nucleus and a free neutron.
   • C) Four hydrogen-1 nuclei fuse to produce one helium-4 nucleus, two positrons, and two neutrinos.
   • D) Six lithium-6 nuclei fuse to produce three helium-4 nuclei and high-energy protons.
2. 2.

   In the deuterium-tritium fusion reaction investigated for commercial energy generation, $^{2}_{1}\text{H} + ^{3}_{1}\text{H} \rightarrow ^{4}_{2}\text{He} + \text{X}$, which particle is represented by X?

   • A) A neutron
   • B) A proton
   • C) A positron
   • D) An alpha particle
3. 3.

   In terms of nuclear binding energy, why does the fusion of very light nuclei such as hydrogen isotopes release large amounts of energy?

   • A) The product nucleus has a higher binding energy per nucleon than the reactants, resulting in a mass defect converted into energy.
   • B) The product nucleus has a lower binding energy per nucleon than the reactants, releasing the surplus nuclear potential energy.
   • C) The total number of nucleons decreases during the reaction, converting the destroyed protons into radiant energy.
   • D) Electrostatic repulsion between the fusing nuclei permanently destabilizes the nucleons, discharging their internal binding energy.
4. 4.

   Which of the following conditions represents the primary barrier that requires nuclear fusion reactions to operate at temperatures of millions of kelvins?

   • A) Strong nuclear forces repelling identical nucleons at short range
   • B) High critical mass thresholds necessary to sustain a neutron cascade
   • C) Electrostatic repulsion between positively charged atomic nuclei
   • D) Electron degeneracy pressure resisting contraction within the plasma
5. 5.

   Which of the following statements correctly describes the process of nuclear fusion?

   • A) It is the combination of two light atomic nuclei to form a heavier nucleus, releasing energy as a result of a mass defect.
   • B) It is the splitting of a heavy, unstable nucleus into two smaller nuclei triggered by the capture of a thermal neutron.
   • C) It is the spontaneous emission of alpha particles and gamma rays from an unstable nucleus to achieve radioactive stability.
   • D) It is a chemical reaction involving the sharing or transfer of valence electrons between atoms at ambient temperatures.

Answers and step-by-step solutions appear after you finish the test.