Paper 1 · People, Development and Environment
UGC NET June 2024 Re-Exam (26.08.2024) Shift-II
Moderators in nuclear reactors are substances which are described by which of the following? Choose the correct answer from the options given below.
- 1. Which slow down the speed of neutrons
- 2. Which limit the chain reaction
- 3. Which help maintain the chain reaction
- 4. Without which the chain reaction would stop in most nuclear reactors
- 5. Such as heavy water or D2O
A1, 2, 3 and 4 only
B1, 3, 4 and 5 only ✓ Correct
C2, 3 and 4 only
D1, 2 and 5 only
Correct answer: (B) 1, 3, 4 and 5 only — Moderators are described by statements 1, 3, 4 and 5, so the answer is 1, 3, 4 and 5.
Explanation
★Moderators are described by statements 1, 3, 4 and 5, so the answer is 1, 3, 4 and 5.
★A moderator slows down the fast neutrons in a reactor, so statement 1 applies.
★By slowing neutrons it helps sustain the chain reaction, so statement 3 applies.
★Without a moderator the chain reaction would stop in most reactors, so statement 4 applies.
★Heavy water, or D2O, is a common moderator, so statement 5 applies.
★A moderator sustains rather than limits the chain reaction, so statement 2 is excluded.
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