If a proton and an anti-proton come close to each other and annihilate, how much energy will be released?

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?

The mass defect of $ { }_{2}^{4} He $ is $ 0.03 \ u $. The binding energy per nucleon of helium (in $ MeV $ ) is

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 $.........\,MeV$.

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

If the speed of light were $2/3$ of its present value,the energy released in a given atomic explosion will be decreased by a fraction: