If $M$ is the atomic mass and $A$ is the mass number,the packing fraction is given by

If an electron and a positron annihilate,then the energy released is

Which of the following statements is correct?

The binding energy for the following nuclear reactions are expressed in $MeV$.
${ }_2 He ^3+{ }_0 n ^1 \rightarrow{ }_2 He ^4+20 \ MeV$
${ }_2 He ^4+{ }_0 n ^1 \rightarrow{ }_2 He ^5-0.9 \ MeV$
If $X_3, X_4, X_5$ denote the stability of ${ }_2 He ^3, { }_2 He ^4$ and ${ }_2 He ^5$, respectively, then the correct order is:

If the binding energy per nucleon for $\,_3^7\,Li\,\,$ and $\,_2^4\,\,He$ are $5.60 \,MeV$ and $7.06 \,MeV$ respectively, then the energy of the proton in the reaction $p\,\, + \,\,_3^7\,\,Li\,\, \to \,\,2\,_2^4\,\,He$ must be .......... $MeV$.

The binding energy per nucleon for ${O^{16}}$ and ${O^{17}}$ are $7.97 \, MeV$ and $7.75 \, MeV$ respectively. How much energy in $MeV$ is required to remove one neutron from ${O^{17}}$?