Q21. Which of the following statements accurately describes the fusion process in stars?
a) Fusion reactions primarily involve the combination of heavier elements to form lighter elements.
b) Fusion reactions release energy primarily in the form of chemical bonds.
c) Fusion reactions in stars occur spontaneously without the need for high temperatures and pressures.
d) Fusion reactions in stars involve the conversion of hydrogen into helium.
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Correct Answer: d) Fusion reactions in stars involve the conversion of hydrogen into helium.
Explanation: In stars like the Sun, nuclear fusion reactions occur in the core, where the high temperatures and pressures allow hydrogen nuclei (protons) to fuse together to form helium nuclei. This process, known as hydrogen fusion or the proton-proton chain, releases large amounts of energy and is the primary source of a star’s luminosity and heat.
Q22. Which of the following factors limits the efficiency of current nuclear fusion experiments?
a) Lack of available fusion fuels
b) Difficulty in achieving high enough temperatures
c) Inability to control the fusion process
d) Excessive production of radioactive waste
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Correct Answer: b) Difficulty in achieving high enough temperatures
Explanation: One of the primary challenges in current nuclear fusion experiments is achieving and maintaining the high temperatures and pressures required for sustained fusion reactions. While progress has been made in confining and heating fusion plasmas, achieving the necessary conditions for net energy gain remains a significant technical hurdle.
Q23. What is the primary advantage of nuclear fusion compared to nuclear fission in terms of safety?
a) Nuclear fusion reactors produce no radioactive waste.
b) Nuclear fusion reactions do not involve the risk of meltdowns.
c) Nuclear fusion reactions do not produce harmful radiation.
d) Nuclear fusion reactors have a lower risk of criticality accidents.
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Correct Answer: b) Nuclear fusion reactions do not involve the risk of meltdowns.
Explanation: One of the key safety advantages of nuclear fusion compared to nuclear fission is that fusion reactions do not involve the risk of meltdowns. Fusion reactions occur only under very specific conditions of temperature and pressure, and if those conditions are not met, the reaction simply ceases, minimizing the risk of catastrophic accidents.
Q24. Which of the following elements is used as a fuel in most experimental fusion reactors?
a) Uranium
b) Hydrogen isotopes
c) Plutonium
d) Thorium
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Correct Answer: b) Hydrogen isotopes
Explanation: Most experimental fusion reactors use hydrogen isotopes, particularly deuterium and tritium, as fuel for fusion reactions. Deuterium is abundant in water, while tritium can be produced from lithium, making hydrogen-based fusion a potentially sustainable and abundant energy source.
Q25. What is the name of the largest international nuclear fusion research project aimed at achieving sustained fusion energy?
a) ITER (International Thermonuclear Experimental Reactor)
b) NIF (National Ignition Facility)
c) JET (Joint European Torus)
d) Wendelstein 7-X
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Correct Answer: a) ITER (International Thermonuclear Experimental Reactor)
Explanation: ITER (International Thermonuclear Experimental Reactor) is the largest international nuclear fusion research project, currently under construction in Cadarache, France. It aims to demonstrate the feasibility of sustained nuclear fusion energy production by creating and maintaining a burning plasma for extended periods.
Q26. What is the primary fuel for the fusion reactions expected to occur in the core of a tokamak reactor?
a) Deuterium
b) Uranium-235
c) Thorium
d) Plutonium-239
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Correct Answer: a) Deuterium
Explanation: Deuterium is one of the primary fuels for fusion reactions in tokamak reactors. Tokamaks are a type of magnetic confinement fusion device designed to contain and stabilize the high-temperature plasma where fusion reactions occur. Deuterium is abundant and can be extracted from water.
Q27. Which of the following confinement methods involves compressing and heating a small target containing fusion fuel to initiate fusion reactions?
a) Inertial confinement
b) Magnetic confinement
c) Electrostatic confinement
d) Gravitational confinement
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Correct Answer: a) Inertial confinement
Explanation: Inertial confinement is a fusion confinement method that involves compressing and heating a small target containing fusion fuel, typically deuterium and tritium, using intense laser or particle beams. The rapid compression and heating of the fuel cause it to reach the high temperatures and pressures necessary for fusion reactions to occur.
Q28. What is the primary challenge associated with achieving sustained nuclear fusion reactions for practical energy production?
a) Containment of the fusion plasma
b) Availability of fusion fuels
c) Control of the fusion process
d) Prevention of radioactive waste
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Correct Answer: a) Containment of the fusion plasma
Explanation: One of the primary challenges associated with achieving sustained nuclear fusion reactions 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.
Q29. Which of the following fusion reactions is considered to be an advanced concept for future fusion power plants due to its potential for fuel self-sufficiency?
a) Deuterium-tritium fusion
b) Deuterium-deuterium fusion
c) Tritium-tritium fusion
d) Proton-boron fusion
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Correct Answer: d) Proton-boron fusion
Explanation: Proton-boron fusion, also known as p-B fusion or aneutronic fusion, is considered an advanced concept for future fusion power plants. Unlike deuterium-tritium fusion, which requires the breeding of tritium fuel, proton-boron fusion uses abundant and non-radioactive fuel sources and produces primarily charged particles, reducing the need for complex radiation shielding and heat conversion systems.
Q30. What is the primary advantage of using magnetic confinement for fusion reactions?
a) Lower energy requirements
b) Higher temperatures achieved
c) Longer plasma confinement times
d) Greater simplicity of reactor design
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Correct Answer: c) Longer plasma confinement times
Explanation: Magnetic confinement fusion devices, such as tokamaks and stellarators, offer the advantage of longer plasma confinement times compared to other confinement methods. By using magnetic fields to contain and stabilize the fusion plasma, these devices can sustain fusion reactions for extended periods, allowing for more efficient energy production.