Question 3: Atoms & Nuclei

Question

Assertion : Heavy water is used to slow
neutron in nuclear reactor.
Reason : It does not react with slow neutron
and mass of deuterium is comparable to the
neutron.

Accepted Answer

Heavy water $$\left(\mathrm{D}_2 \mathrm{O}\right)$$ is used to slow down fast moving neutrons in nuclear reactor, hence it is called moderator. It does remove neutrons from the system by absorbing them. When fast moving neutrons are passed through heavy water $$\left(\mathrm{D}_2 \mathrm{O}\right)$$, then they make elastic collisions with protons, which have comparatively much smaller than velocities. In few interactions, the velocities of neutrons get interchanged with those of protons. Heavy water does not react with slow moving neutrons, i.e. it slow down-fast moving neutrons. Hence, assertion and reason both are true and reason is the correct explanation of assertion.

Answer

If both assertion and reason are true and reason is the correct explanation of assertion.

Answer

If both assertion and reason are true, but reason is not the correct explanation of assertion.

Answer

If assertion is true, but reason is false.

Answer

If both assertion and reason are false.

Atoms & Nuclei

Assertion : Heavy water is used to slow neutron in nuclear reactor. Reason : It does not react with slow neutron and mass of deuterium is comparable to the neutron.

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