(N/A) The two main features of the binding energy per nucleon curve lead to the following conclusions:
$(i)$ The nuclear force is attractive and sufficiently strong to produce a binding energy per nucleon of approximately $8 \text{ MeV}$ for nuclei with $30 < A < 170$. This indicates that the nuclear force is short-ranged and exhibits the property of saturation.
$(ii)$ For very heavy nuclei $(A > 170)$,the binding energy per nucleon decreases. This occurs because the long-range Coulomb repulsion between protons becomes significant,reducing the stability. Consequently,if a heavy nucleus $(A = 240)$ splits into two lighter nuclei $(A = 120)$,the nucleons become more tightly bound,releasing energy. This process is known as nuclear fission.
$(iii)$ For very light nuclei $(A \leq 10)$,the binding energy per nucleon is low. When two light nuclei fuse to form a heavier nucleus,the resulting nucleus is more tightly bound,releasing energy. This process is known as nuclear fusion,which powers the Sun and hydrogen bombs.