Nuclear chemistry: decay modes, nuclear reactions, Q‑value, cross sections and photonuclear reactions - One Line Questions

1. A nucleus that undergoes alpha decay will have its atomic number decreased by: — 2
2. A nucleus that undergoes alpha decay will have its mass number decreased by: — 4
3. Beta-minus decay increases the atomic number of the nucleus by: — 1
4. Beta-plus decay decreases the atomic number of the nucleus by: — 1
5. Nuclear fusion is the process where: — Light nuclei combine to form a heavier nucleus
6. A larger cross section for a particular nuclear reaction implies: — A higher probability of the reaction occurring
7. What is electron capture? — A nucleus absorbing an electron from its inner shell, converting a proton to a neutron
8. Which of the following best describes the process of pair production induced by a high-energy photon? — A photon creates an electron-positron pair near a nucleus.
9. Which type of decay is often accompanied by gamma emission? — All of the above
10. Which of the following is NOT a fundamental decay mode? — Spontaneous fission
11. Which nuclear decay mode does not change the mass number of the nucleus? — Gamma decay
12. Which particle is primarily responsible for initiating a chain reaction in nuclear fission? — Neutron
13. Gamma decay primarily involves the release of energy in the form of: — High-energy photons
14. Photonuclear reactions are typically observed with gamma rays of energy: — Around 10 MeV
15. Which type of radioactive decay involves the emission of an alpha particle? — Alpha decay
16. What is the term for a nuclear reaction where the incident particle transfers energy and momentum to the target nucleus, but does not form a compound nucleus? — Direct reaction
17. The Q-value calculation for a nuclear reaction relies on the principle of: — Conservation of energy and mass defect
18. What is the term for a nuclear reaction where the incident particle is absorbed by the target nucleus, and the resulting excited nucleus immediately decays? — Compound nucleus reaction
19. In beta-plus decay, what particle is emitted along with a neutrino? — Positron
20. Photonuclear reactions involve the interaction of gamma rays with: — Nuclei
21. What is the primary characteristic of beta-minus decay? — Emission of an electron and an antineutrino
22. Which of the following is a characteristic feature of photonuclear reactions? — Emission of neutrons or protons
23. A nuclear reaction with a positive Q-value is: — Exothermic
24. A nuclear reaction with Q = 0 is: — Elastic
25. A nuclear reaction that requires energy input to proceed is: — Endothermic
26. Which type of nuclear reaction involves the interaction of two nuclei to form a heavier nucleus? — Fusion
27. What is the primary difference between nuclear fission and nuclear fusion? — Fission splits heavy nuclei; fusion combines light nuclei.
28. What is the process called when a nucleus splits into two or more smaller nuclei? — Fission
29. The probability of a neutron-induced reaction is often described by its: — Cross section
30. What is the significance of the 'binding energy per nucleon' in nuclear reactions? — It explains why fusion and fission release energy.
31. The Q-value of a nuclear reaction is essentially the difference in: — Masses of reactants and products
32. In nuclear reactions, 'cross section' is usually measured in units of: — barns (1 barn = 10^-28 m^2)
33. Photonuclear reactions are also known as: — Photodisintegration
34. Which type of nuclear reaction is the primary energy source of stars like the Sun? — Nuclear fusion
35. In nuclear reactions, 'cross section' is a measure of: — Reaction probability
36. In the context of nuclear reactions, what does 'cross section' depend on? — Both the target nucleus and the incident particle, as well as their energy
37. In a photonuclear reaction, a gamma ray photon can eject a particle from the nucleus. This process is called: — Photodisintegration
38. What is the phenomenon where a nucleus absorbs a gamma ray photon and becomes excited? — Photoexcitation
39. An endothermic nuclear reaction is characterized by a Q-value that is: — Negative
40. What happens to the number of protons and neutrons in beta-minus decay? — Protons increase by 1, neutrons decrease by 1.
41. What happens to the number of protons and neutrons in beta-plus decay? — Protons decrease by 1, neutrons increase by 1.
42. What is the primary consequence of a nuclear reaction with a large positive Q-value? — Significant energy release
43. A nuclear reaction where a nucleus is bombarded by a particle, leading to a change in its composition, is known as: — Induced nuclear reaction
44. The energy released in nuclear fusion reactions primarily comes from: — Both A and C
45. What does the Q-value of a nuclear reaction represent? — The energy released or absorbed in the reaction
46. What does the 'cross section' conceptually represent in nuclear physics? — The probability of a specific nuclear interaction occurring
47. The term 'decay modes' refers to: — The different ways an unstable nucleus can transform into a more stable one
48. The 'decay modes' of a radioactive isotope describe: — The pathways by which it transforms
49. The term 'cross section' in nuclear physics is analogous to: — The target area presented to an incident particle
50. What are the primary products of the fission of Uranium-235 by a thermal neutron? — Two lighter nuclei and several neutrons
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