For which mass number range is the binding energy per nucleon maximum?

The binding energies of $_1H^2$,$_2He^4$,$_{26}Fe^{56}$,and $_{92}U^{235}$ are $2.22 \ MeV$,$28.3 \ MeV$,$492 \ MeV$,and $1786 \ MeV$ respectively. Which nucleus is the most stable?

What is the energy equivalent to one kilogram of mass?

$A$ radioactive nucleus has specific binding energy $E_{1}$. It emits an $\alpha$-particle. The resulting nucleus has specific binding energy $E_{2}$. Then

Binding energy per nucleon of a fixed nucleus $X^A$ is $8 \ MeV$. It absorbs a neutron moving with kinetic energy $2 \ MeV$ and converts into $Y$,emitting two photons of energy $1 \ MeV$ and $4 \ MeV$ respectively one after the other. The binding energy per nucleon of $Y$ (in $MeV$) is:

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: