Two lighter nuclei combine to form a comparatively heavier nucleus by the relation given below:
${ }_{1}^{2} X +{ }_{1}^{2} X ={ }_{2}^{4} Y$
The binding energies per nucleon of ${ }_{1}^{2} X$ and ${ }_{2}^{4} Y$ are $1.1 \, MeV$ and $7.6 \, MeV$ respectively. The energy released in this process is in $MeV$.

Slowing down of neutrons: In a nuclear reactor,a neutron of high speed (typically $10^{7} \; m s^{-1}$) must be slowed to $10^{3} \; m s^{-1}$ so that it can have a high probability of interacting with isotope $^{235}_{92}U$ and causing it to fission. Show that a neutron can lose most of its kinetic energy in an elastic collision with a light nucleus like deuterium or carbon,which has a mass of only a few times the neutron mass. The material making up the light nuclei,usually heavy water $(D_{2}O)$ or graphite,is called a moderator.

$A$ nuclear fuel rod generates energy at a rate of $5 \times 10^8 \,W/m^3$. It is in the shape of a cylinder of radius $4.0 \,mm$ and length $0.20 \,m$. $A$ coolant of specific heat $4 \times 10^3 \,J \cdot kg^{-1} \cdot K^{-1}$ flows past it at a rate of $0.2 \,kg/s$. The temperature rise in this coolant is approximately ............ $^{\circ}C$.

$1 \, g$ of hydrogen is converted into $0.993 \, g$ of helium in a thermonuclear reaction. The energy released is

Which reaction is not part of the proton-proton cycle?

The binding energy per nucleon for deuteron $(_1^2H)$ and helium $(_2^4He)$ nuclei are $1.1 \, MeV$ and $7 \, MeV$ respectively. Calculate the energy released in $MeV$ when two deuteron nuclei fuse to form a helium nucleus.