TRB PG Assistant - Nuclear fission and fusion, chain reactions, fertile and fissile isotopes and radiation hazards Online Test (MCQ Quiz)

1. What is the process by which a heavy atomic nucleus splits into two or more lighter nuclei, releasing a large amount of energy?

A) Nuclear fusion B) Nuclear fission C) Radioactive decay D) Spallation

2. Which of the following is a primary requirement for initiating a nuclear fission chain reaction?

A) High temperature B) High pressure C) Sufficient quantity of fissile material D) Presence of a strong magnetic field

3. What is the term for an isotope that can undergo fission when it absorbs a neutron?

A) Fertile isotope B) Fissile isotope C) Radioactive isotope D) Stable isotope

4. Which of the following is a common example of a fissile isotope used in nuclear reactors?

A) Uranium-238 B) Thorium-232 C) Uranium-235 D) Plutonium-239

5. What is a 'fertile' isotope in the context of nuclear reactions?

A) An isotope that readily undergoes fission B) An isotope that can be converted into a fissile isotope C) An isotope that emits alpha particles D) An isotope with a very long half-life

6. Which of the following is a fertile isotope that can be converted into a fissile isotope (Plutonium-239)?

A) Uranium-235 B) Thorium-232 C) Uranium-238 D) Plutonium-238

7. What type of radiation consists of high-energy photons and has no mass or charge?

A) Alpha particles B) Beta particles C) Neutrons D) Gamma rays

8. Which type of radiation is essentially a helium nucleus (2 protons and 2 neutrons)?

A) Alpha particles B) Beta particles C) Gamma rays D) X-rays

9. Beta particles are actually:

A) Protons B) Neutrons C) Electrons or positrons D) Helium nuclei

10. What is the primary hazard associated with neutron radiation?

A) It can cause skin burns B) It is highly penetrating and can damage living tissue C) It can be easily stopped by a sheet of paper D) It is primarily an external hazard

11. A 'chain reaction' in nuclear fission refers to:

A) The decay of a single nucleus B) The process where neutrons released from one fission cause further fissions C) The fusion of two light nuclei D) The emission of gamma rays

12. What condition is necessary for a nuclear chain reaction to be sustained (i.e., not die out)?

A) The average number of neutrons produced per fission that cause further fission must be less than one. B) The average number of neutrons produced per fission that cause further fission must be exactly one. C) The average number of neutrons produced per fission that cause further fission must be greater than one. D) The fissile material must be in a gaseous state.

13. A 'critical' chain reaction occurs when:

A) The rate of fission is decreasing. B) The rate of fission is increasing exponentially. C) The rate of fission remains constant. D) The chain reaction stops completely.

14. An 'uncontrolled' chain reaction, as in a nuclear weapon, is characterized by:

A) A constant rate of fission. B) A rapidly increasing rate of fission. C) A decreasing rate of fission. D) A very slow and steady release of energy.

15. A 'controlled' chain reaction, as in a nuclear power reactor, is characterized by:

A) A rapidly increasing rate of fission. B) A decreasing rate of fission. C) A constant and manageable rate of fission. D) No neutrons being produced.

16. What is the main source of energy released during nuclear fission?

A) The breaking of chemical bonds B) The conversion of mass into energy (E=mc²) C) The excitation of electrons D) The kinetic energy of emitted particles

17. What are the typical fission products of Uranium-235?

A) Two lighter nuclei with approximately half the mass of Uranium-235 B) Three lighter nuclei with significantly less mass C) The same Uranium-235 nucleus D) Helium and hydrogen nuclei

18. Which of the following is NOT a form of ionizing radiation?

A) Alpha particles B) Beta particles C) Gamma rays D) Visible light

19. What is the primary mechanism by which ionizing radiation damages biological tissues?

A) Heating the tissue B) Causing chemical changes in molecules, including DNA C) Increasing the blood flow D) Stimulating cell growth

20. What is the process by which two light atomic nuclei combine to form a single heavier nucleus, releasing energy?

A) Nuclear fission B) Nuclear fusion C) Radioactive decay D) Electron capture

21. Nuclear fusion requires what conditions to occur?

A) Low temperatures and high pressures B) High temperatures and high pressures C) Low temperatures and low pressures D) Extremely low temperatures and low pressures

22. Which of the following is the primary energy source of stars, including our Sun?

A) Nuclear fission B) Chemical reactions C) Nuclear fusion D) Gravitational collapse

23. What are the main reactants in the fusion process that powers the Sun?

A) Carbon and Oxygen B) Helium and Lithium C) Hydrogen and Helium D) Uranium and Plutonium

24. What is a major challenge in achieving controlled nuclear fusion on Earth?

A) Containing the extremely high temperatures required B) Finding sufficient amounts of fissile material C) Preventing the release of alpha particles D) Slowing down the fusion reaction

25. Which type of radiation has the greatest penetrating power and requires thick shielding like lead or concrete?

A) Alpha particles B) Beta particles C) Gamma rays D) Neutrons

26. What is the term for the minimum amount of fissile material needed to sustain a chain reaction?

A) Critical mass B) Fertile mass C) Effective mass D) Minimum mass

27. The process of converting a fertile isotope like Uranium-238 into a fissile isotope like Plutonium-239 involves:

A) Absorption of a proton B) Absorption of a neutron followed by decay C) Emission of an alpha particle D) Fusion with another nucleus

28. Which of the following is a significant source of background radiation?

A) Microwave ovens B) Household cleaning products C) Cosmic rays and naturally occurring radioactive elements in the Earth's crust D) Mobile phone signals

29. What is a 'prompt neutron' in nuclear fission?

A) A neutron emitted after a delay due to radioactive decay of fission fragments B) A neutron emitted almost instantaneously during the fission process C) A neutron captured by the fissile nucleus D) A neutron absorbed by control rods

30. What are 'delayed neutrons' in nuclear fission?

A) Neutrons emitted immediately during fission B) Neutrons emitted by fission products after beta decay C) Neutrons that do not cause further fission D) Neutrons absorbed by control rods

31. Why are delayed neutrons important in the control of nuclear reactors?

A) They cause the chain reaction to stop. B) They allow for a more gradual and controllable increase in reactivity. C) They are the primary source of energy. D) They are easily shielded.

32. What is a common method used to shield against alpha radiation?

A) Several meters of concrete B) A thin sheet of paper or the outer layer of skin C) A few centimeters of lead D) A strong magnetic field

33. What is a common method used to shield against beta radiation?

A) A thin sheet of paper B) A few millimeters of aluminum or plastic C) Thick concrete walls D) Water

34. What is the term for the process where a radioactive nucleus loses energy by emitting particles or electromagnetic waves?

A) Nuclear fission B) Nuclear fusion C) Radioactive decay D) Spallation

35. Which isotope is often used as a target for producing transuranic elements through neutron bombardment?

A) Uranium-235 B) Plutonium-239 C) Uranium-238 D) Thorium-232

36. What is the primary hazard of internal radioactive contamination?

A) External burns B) High dose of radiation delivered directly to internal organs C) Temporary sickness D) Electromagnetic interference

37. What is a 'breeder reactor' designed to do?

A) Slow down neutrons for fission B) Produce more fissile material than it consumes C) Absorb excess neutrons D) Generate heat for electricity only

38. Which of the following is a potential long-term health effect of significant radiation exposure?

A) Improved eyesight B) Increased lifespan C) Increased risk of cancer D) Enhanced cognitive function

39. What is the unit of absorbed radiation dose commonly used in medicine and health physics?

A) Becquerel (Bq) B) Curie (Ci) C) Gray (Gy) D) Sievert (Sv)

40. What is the unit of equivalent dose or effective dose, which accounts for the biological effectiveness of different types of radiation?

A) Gray (Gy) B) Becquerel (Bq) C) Rad D) Sievert (Sv)

41. What is the term for the phenomenon where a neutron is captured by a nucleus without causing fission?

A) Neutron scattering B) Neutron activation C) Neutron absorption D) Neutron capture

42. Neutron activation is the process by which:

A) A stable nucleus becomes radioactive after absorbing a neutron. B) A radioactive nucleus splits into lighter elements. C) Two nuclei fuse together. D) A neutron is emitted from a nucleus.

43. What is the main reason for using moderators (like water or graphite) in nuclear reactors?

A) To absorb neutrons and control the reaction rate. B) To slow down fast neutrons to thermal energies, making them more likely to cause fission in Uranium-235. C) To reflect neutrons back into the core. D) To initiate the fission process.

44. Control rods in a nuclear reactor are typically made of materials that:

A) Produce neutrons B) Absorb neutrons strongly C) Reflect neutrons D) Slow down neutrons

45. What is a common material used for control rods in nuclear reactors?

A) Uranium B) Graphite C) Cadmium or Boron D) Water

46. What is the term for an isotope that can be readily fissioned by fast neutrons?

A) Fertile isotope B) Fissile isotope C) Fissionable isotope D) Radiogenic isotope

47. Uranium-238 is considered fissionable but not fissile because:

A) It cannot absorb neutrons at all. B) It requires very high energy neutrons to fission, unlike thermal neutrons. C) It decays rapidly. D) It is a stable isotope.

48. What is the most common product of nuclear fission that poses a long-term waste disposal challenge?

A) Unreacted Uranium B) Plutonium-239 C) Fission product isotopes with long half-lives (e.g., Cesium-137, Strontium-90) D) Neutrons

49. Which process involves the release of energy due to the strong nuclear force binding nucleons together?

A) Chemical reactions B) Nuclear fission and fusion C) Thermonuclear reactions D) Combustion

Nuclear fission and fusion, chain reactions, fertile and fissile isotopes and radiation hazards - Online Test

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