Moderator is a substance that ..................... the neutrons in a nuclear reactor.

Q.

Q. With reference to the parts of a Nuclear reactor, consider the following statements:

Select the correct answer using the codes given below:

1. 
   1 only
2. 
   2 only
3. 
   Both 1 and 2
4. 
   Neither 1 nor 2

Q.

The velocity of neutrons in a nuclear reactor is slowed down by using:

Q. In a nuclear reactor, 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

Q. Consider the following substances:
$1.$ Heavy water $2.$ Graphite
Which of the substances given above is/are used as a moderator in a nuclear reactor?