The given below 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) $A+B\to C+\epsilon$   ii) $C\to A+B+\epsilon$  iii) $D+E\to F+\epsilon$  iv) $F\to D+E+\epsilon$ 
where $\epsilon$ is the energy released. In which reactions is $\epsilon$ positive?

In nuclear physics, the phenomenon termed fusion occurs when two nucleons coalesce to produce a third, resulting in the liberation of energy. Conversely, fission occurs when a singular nucleus undergoes division into two, accompanied by the release of energy. The propensity for fusion reactions is more pronounced in the context of light elements, whereas fission reactions predominantly manifest in heavy elements.