What does the binding energy per nucleon show?

If the binding energy per nucleon for $_3{Li}^7$ and $_2{He}^4$ nuclei are $5.60 \, MeV$ and $7.06 \, MeV$ respectively,then the energy released in the reaction $_3{Li}^7 + _1H^1 \rightarrow 2 \, _2{He}^4$ is ...... $MeV$.

For the decay of a nucleus,which of the following is $NOT$ a possible reason?

$\gamma$-rays radiation can be used to create an electron-positron pair. In this process of pair production,$\gamma$-rays energy cannot be less than ....... $MeV$.

In the nuclear reaction,$_1H^2 + _1H^2 \to _0n^1 + _2He^3$. If the binding energy of deuteron is $2.23 \ MeV$ and the $Q$-value of the reaction is $3.27 \ MeV$,then the binding energy of $_2He^3$ is ......... $MeV$.

The masses of a proton, neutron, and helium nucleus are $1.0073\,u$, $1.0087\,u$, and $4.0015\,u$ respectively. The binding energy of the helium nucleus is $.........\,MeV$.