Nuclear fission is possible because the binding energy per nucleon ...

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

The figure shows a plot of binding energy per nucleon $E_b$ against the nuclear mass number $A$. $A, B, C, D, E, F$ correspond to different nuclei. Consider four reactions:
$(i) A + B \to C + \varepsilon$
$(ii) C \to A + B + \varepsilon$
$(iii) D + E \to F + \varepsilon$
$(iv) F \to D + E + \varepsilon$
Here, $\varepsilon$ is the energy released. In which reactions is $\varepsilon$ > 0?

In the nuclear process $n \to p + e^- + \bar{\nu}$,if the masses of proton,neutron,and electron are $1.6725 \times 10^{-27} \ kg$,$1.6747 \times 10^{-27} \ kg$,and $9 \times 10^{-31} \ kg$ respectively,then the energy released is ...... $MeV$.

The binding energy per nucleon versus mass number curve for nuclei is shown in the figure. $W, X, Y$ and $Z$ are four nuclei indicated on the curve. The process that would release energy is

One atomic mass unit is equivalent to .............. $MeV$ energy.