Draw the nature of the graph of average binding energy per nucleon against atomic mass number and explain its notable points.

(N/A) The graph of binding energy per nucleon $(E_{bn})$ versus the atomic mass number $(A)$ is shown in the figure.
The main features of the plot are as follows:
$(i)$ The binding energy per nucleon,$E_{bn}$,is practically constant and independent of the atomic mass number for nuclei of intermediate mass number $(30 < A < 170)$. The maximum value of $E_{bn}$ is approximately $8.75 \text{ MeV/nucleon}$,which occurs for the iron $(^{56}\text{Fe})$ nucleus. For heavy nuclei like uranium $(^{238}\text{U})$,the value of $E_{bn}$ decreases to about $7.6 \text{ MeV/nucleon}$.
$(ii)$ $E_{bn}$ is lower for both light nuclei $(A < 30)$ and heavy nuclei $(A > 170)$,indicating that they are less stable compared to intermediate-mass nuclei. From the graph,it is evident that the binding energy per nucleon for the deuteron $(^{2}_{1}\text{H})$ is the lowest.
$(iii)$ For light nuclei,stability is generally achieved when the ratio of neutrons to protons is approximately $1:1$. However,for heavy nuclei,this ratio increases to about $3:2$ to compensate for the increased electrostatic repulsion between protons.