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

In the given nuclear reaction
${ }_{4}^{9} Be+{ }_{2}^{4} He \rightarrow{ }_{6}^{12} C+X$
$X$ represents $\qquad$

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?

Fusion reaction takes place at high temperature because

Which one of the following nuclear reactions is a source of energy in the sun?

Consider the fission of $_{92}^{238} U$ by fast neutrons. In one fission event,no neutrons are emitted and the final end products,after the beta decay of the primary fragments,are $_{58}^{140} Ce$ and $_{44}^{99} Ru$. Calculate the $Q$-value for this fission process. The relevant atomic and particle masses are:
$m(_{92}^{238} U) = 238.05079 \; u$
$m(_{58}^{140} Ce) = 139.90543 \; u$
$m(_{44}^{99} Ru) = 98.90594 \; u$
$m(_{0}^{1} n) = 1.008665 \; u$