Which element has the maximum binding energy per nucleon? Write down its value.

The mass of a nucleus,a neutron,and a proton are $M$,$M_n$,and $M_p$ respectively. Then which of the following is true?

Assertion : In a decay process of a nucleus, the mass of products is less than that of the parent.
Reason : The rest mass energy of the products must be less than that of the parent.

What is the energy produced in $MeV$ when the mass equivalent to $1$ proton is completely converted into energy?

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:

The positions of four different nuclei in the binding energy curve are shown in the figure. The process that might not proceed spontaneously is