The binding-energy-per-nucleon (AEb) of nuclei varies systematically with mass number A. Answer the following in a logical sequence.
(a) Draw a neat, labelled sketch of the qualitative variation of AEb with A for nuclei from A=1 to A≈240.
(b) On your sketch clearly mark and name the regions of (i) light nuclei (A<20), (ii) medium-mass nuclei (20<A<80) and (iii) heavy nuclei (A>200).
(c) Explain why the curve rises steeply for very small A, attains a broad maximum near A≈56, and then falls slowly for very large A.
(d) Using only the features of the curve you have drawn, justify qualitatively why (i) fusion of two light nuclei and (ii) fission of a very heavy nucleus are both exothermic processes.