The above is a plot of binding energy per nucleon $$E_b$$, against the nuclear mass $$M$$; $$A, B, C, D, E, F$$ correspond to different nuclei. Consider four reactions: (i) $$A + B \to C + \varepsilon$$ (ii) $$C \to A + B + \varepsilon$$ (iii) $$D + E \to F + \varepsilon$$ and (iv) $$F \to D + E + \varepsilon$$ where $$\varepsilon$$ is the energy released? In which reactions is $$\varepsilon$$ positive?