For a hypothetical $A^{+}-B$ ion pair, attractive and repulsive energies $E_A$ and $E_R,$ respectively, depend on the distance between the ions r $,$ according to

$E_A=-\frac{A}{r}$

$E_R=\frac{B}{r^8}$

Fort these expressions, energies are expressed in electron volts for $A^{+}-B$ pair, and r is the distance in anometers. The net energy $E_N$ is just the sum of the two expressions above.

a$)$ Superimpose on a single plot $E_N,E_A,$ and $E_R$ versus interatomic distance up to r nm given in the table below.

b$)$ On the basis of this plot, determine $($i$)$ the equilibrium spacing $r_0$ between $A+$ and B $-$ ions, and $($ii$)$ the magnit$$de of the bonding energy $E_0$ between the ions.

A$=1,558$

B$=8,36$E $-0,6$

r$($nm$)=0,095$