Which of the following is the best neutron moderator compared to all others?

The energy of the fast neutrons emitted in a nuclear fission reactor is approximately $\qquad$ .

If in a nuclear fusion process the masses of the fusing nuclei are ${m_1}$ and ${m_2}$ and the mass of the resultant nucleus is ${m_3}$, then

Consider the $D-T$ reaction (deuterium-tritium fusion):
$_{1}^{2} H +_{1}^{3} H \rightarrow_{2}^{4} He + n$
$(a)$ Calculate the energy released in $MeV$ in this reaction from the data:
$m(_{1}^{2} H) = 2.014102 \; u$
$m(_{1}^{3} H) = 3.016049 \; u$
$(b)$ Consider the radius of both deuterium and tritium to be approximately $2.0 \; fm$. What is the kinetic energy needed to overcome the Coulomb repulsion between the two nuclei? To what temperature must the gas be heated to initiate the reaction?

The nucleus of $_6C^{12}$ absorbs a neutron and emits a $\beta$-particle. The resulting nucleus is ........

When two deuterium nuclei fuse together to form a tritium nucleus,what is the other product released?