91. What is the primary purpose of using deuterium in nuclear reactors?
- a) To generate electricity directly
- b) To act as a neutron moderator
- c) To absorb gamma radiation
- d) To produce heavy water
Answer: b) To act as a neutron moderator
Explanation:
Deuterium is used in nuclear reactors, typically in the form of heavy water, to slow down neutrons and sustain the nuclear fission chain reaction.
92. Which of the following isotopes of hydrogen is most suitable for use in long-term biological studies?
- a) Protium
- b) Deuterium
- c) Tritium
- d) Helium-3
Answer: b) Deuterium
Explanation:
Deuterium is used in biological studies as it is stable and does not pose the radioactive hazards associated with tritium. It is used to study metabolism and other biological processes.
93. Which of the following is true regarding tritium’s half-life?
- a) It is less than a year.
- b) It is approximately 12.3 years.
- c) It is more than 100 years.
- d) It does not decay.
Answer: b) It is approximately 12.3 years.
Explanation:
Tritium has a half-life of about 12.3 years, after which half of the tritium in a sample will have decayed into helium-3 through beta decay.
94. Which isotope of hydrogen is most abundant in the Sun?
- a) Protium
- b) Deuterium
- c) Tritium
- d) None of these
Answer: a) Protium
Explanation:
Protium is the most abundant isotope of hydrogen in the Sun. It undergoes nuclear fusion in the Sun’s core, producing energy through the proton-proton chain reaction.
95. In fusion reactors, why is a combination of deuterium and tritium preferred over other isotopes?
- a) They are the easiest to obtain.
- b) They have the lowest energy requirements for fusion.
- c) They are the most stable.
- d) They produce no neutrons.
Answer: b) They have the lowest energy requirements for fusion.
Explanation:
The fusion of deuterium and tritium requires the lowest temperature and energy compared to other isotopes of hydrogen, making it ideal for use in experimental fusion reactors.
96. Which isotope of hydrogen is produced naturally by cosmic ray interactions in the Earth’s atmosphere?
- a) Protium
- b) Deuterium
- c) Tritium
- d) None of these
Answer: c) Tritium
Explanation:
Tritium is produced naturally in the Earth’s atmosphere when cosmic rays interact with nitrogen and other elements. However, it occurs in very small amounts.
97. Which of the following isotopes is used in heavy water reactors to maintain a sustained nuclear chain reaction?
- a) Protium
- b) Deuterium
- c) Tritium
- d) Oxygen-18
Answer: b) Deuterium
Explanation:
Deuterium, in the form of heavy water (D₂O), is used as a moderator in heavy water reactors to slow down fast neutrons and maintain a sustained nuclear chain reaction.
98. Which isotope of hydrogen is used in glow sticks?
- a) Protium
- b) Deuterium
- c) Tritium
- d) None of these
Answer: c) Tritium
Explanation:
Tritium is used in glow sticks and other luminescent devices, where its radioactive decay causes phosphors to glow without the need for an external power source.
99. Which of the following isotopes of hydrogen has a proton and two neutrons?
- a) Protium
- b) Deuterium
- c) Tritium
- d) None of these
Answer: c) Tritium
Explanation:
Tritium has one proton and two neutrons, making it the heaviest of the three hydrogen isotopes.
100. Which of the following isotopes of hydrogen is commonly used in thermonuclear weapons?
- a) Protium
- b) Deuterium
- c) Tritium
- d) Both b and c
Answer: d) Both b and c
Explanation:
Both deuterium and tritium are used in thermonuclear weapons (hydrogen bombs) as they undergo fusion reactions that release tremendous amounts of energy.
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