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In a nuclear moderators slow down the ne...

In a nuclear moderators slow down the neutrons which come out in a fission process. The moderator used have light nuclei. Heavy nuclei will not serve the purpose because

A

they will break up

B

elastic collision of neutrons with heavy nuclei will not slow them down.

C

the net weight of the reactor would be unbearably high.

D

substances with heavy nuclei do not occur in liquid or gaseous state at room temperature?

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