In a nuclear fusion process,the mass defect is $0.05\%$. How much energy will be released from $1 \, kg$ of mass?

The rest mass of an electron as well as that of a positron is $0.51 \, MeV$. When an electron and a positron annihilate, they produce gamma-rays of wavelength(s):

How much energy is released by the fusion of four hydrogen atoms to form a helium nucleus (in $MeV$)?

What is the amount of energy released by deuterium and tritium fusion (in $,MeV$)?

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 best neutron moderator is: