Q41. What is the primary benefit of nuclear fusion over nuclear fission in terms of fuel availability?
a) Fusion fuels are more abundant and widely distributed.
b) Fusion fuels require less processing and enrichment.
c) Fusion fuels produce less radioactive waste.
d) Fusion fuels have a higher energy density.
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Correct Answer: a) Fusion fuels are more abundant and widely distributed.
Explanation: Fusion fuels, such as isotopes of hydrogen, are more abundant and widely distributed compared to the finite reserves of fissile materials used in nuclear fission, such as uranium and plutonium. Hydrogen isotopes, particularly deuterium, can be extracted from water, providing a virtually limitless fuel source for fusion reactions.
Q42. What is the term for the state in which a nuclear fusion reaction becomes self-sustaining and releases more energy than is required to initiate and maintain the reaction?
a) Ignition
b) Breakeven
c) Criticality
d) Superfusion
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Correct Answer: a) Ignition
Explanation: Ignition refers to the state in which a nuclear fusion reaction becomes self-sustaining and releases more energy than is required to initiate and maintain the reaction. Achieving ignition is a key milestone in fusion research and represents the point at which a fusion reactor becomes capable of producing net energy gain.
Q43. Which of the following elements is commonly used as a fuel in experimental fusion reactors due to its ability to produce tritium through neutron capture?
a) Lithium
b) Boron
c) Helium
d) Beryllium
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Correct Answer: a) Lithium
Explanation: Lithium is commonly used as a fuel in experimental fusion reactors because it can produce tritium through neutron capture reactions. Tritium, an isotope of hydrogen, is essential for fusion reactions involving deuterium-tritium fuel, and lithium serves as a source of tritium in fusion reactors through neutron bombardment.
Q44. What is the primary mechanism by which fusion reactions release energy?
a) Conversion of mass into energy
b) Formation of chemical bonds
c) Absorption of photons
d) Redistribution of electrons
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Correct Answer: a) Conversion of mass into energy
Explanation: Fusion reactions release energy primarily through the conversion of mass into energy, as described by Einstein’s famous equation, E=mc². In fusion reactions, the total mass of the fusion products is slightly less than the mass of the original nuclei, and the mass difference is converted into energy according to the equation.
Q45. Which of the following is a potential application of nuclear fusion other than energy production?
a) Medical imaging
b) Isotope production
c) Waste incineration
d) Carbon capture
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Correct Answer: b) Isotope production
Explanation: Nuclear fusion has potential applications beyond energy production, including the production of isotopes for various purposes. Fusion reactors can produce isotopes used in medical imaging, industrial processes, and scientific research, among other applications, offering advantages such as high purity and minimal radioactive waste generation.
Q46. Which of the following fusion reactor designs aims to achieve ignition by compressing and heating small fuel pellets using intense laser or particle beams?
a) Tokamak
b) Stellarator
c) Inertial confinement reactor
d) Magnetic mirror device
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Correct Answer: c) Inertial confinement reactor
Explanation: Inertial confinement fusion (ICF) reactors aim to achieve fusion ignition by compressing and heating small fuel pellets containing fusion fuel using intense laser or particle beams. This approach, often referred to as “miniature star” concept, involves rapid compression and heating of the fuel to achieve the conditions necessary for fusion reactions.
Q47. Which of the following elements is commonly used as a neutron moderator in some experimental fusion reactors?
a) Boron
b) Carbon
c) Helium
d) Beryllium
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Correct Answer: b) Carbon
Explanation: Carbon is commonly used as a neutron moderator in some experimental fusion reactors to slow down fast neutrons produced by fusion reactions. Slowing down neutrons increases their likelihood of causing further fusion reactions, enhancing the efficiency of the fusion process. Other materials, such as beryllium and water, can also serve as neutron moderators.
Q48. What is the primary advantage of fusion reactions compared to fission reactions in terms of radioactive waste generation?
a) Fusion reactions produce less radioactive waste.
b) Fusion reactions produce no radioactive waste.
c) Fusion reactions produce shorter-lived radioactive waste.
d) Fusion reactions produce heavier radioactive waste.
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Correct Answer: a) Fusion reactions produce less radioactive waste.
Explanation: Fusion reactions produce less radioactive waste compared to fission reactions. While fusion reactions can still produce radioactive byproducts, they typically generate fewer and less long-lived radioactive isotopes, reducing the environmental and health hazards associated with radioactive waste disposal.
Q49. Which of the following fusion reactions is expected to be the primary source of energy in future fusion power plants?
a) Deuterium-tritium fusion
b) Deuterium-deuterium fusion
c) Tritium-tritium fusion
d) Proton-boron fusion
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Correct Answer: a) Deuterium-tritium fusion
Explanation: Deuterium-tritium fusion is expected to be the primary source of energy in future fusion power plants due to its high fusion cross-section and relatively low energy threshold. Deuterium and tritium are isotopes of hydrogen that readily undergo fusion reactions, making them suitable fuels for achieving sustained fusion energy production.
Q50. Which of the following is a major challenge in achieving controlled nuclear fusion for practical energy production?
a) Generation of radioactive waste
b) Containment of the fusion plasma
c) Lack of fusion fuels
d) Safety concerns
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Correct Answer: b) Containment of the fusion plasma
Explanation: One of the major challenges in achieving controlled nuclear fusion for practical energy production is effectively containing and stabilizing the fusion plasma where reactions occur. Maintaining the high temperatures and pressures necessary for fusion while preventing plasma instabilities and heat loss presents significant technical hurdles.