Note in Table 9-2 that the equilibrium separation of the KBr and RbCl molecules is very nearly equal. Compute the exclusion-principle repulsion for these molecules.

Table 9-2 Dissociation energies E, and equilibrium separations ro for several ionic molecules* in the gaseous state Dissociation energy (eV) Equilibrium separation (nm) Molecule NaCl NaF NaH NaBr LiCl LiH Lil KCI KBr RbF RbCl CSI 4.27 5.34 1.92 3.81 4.86 2.47 3.58 4.49 3.94 5.12 4.43 3.50 0.236 0.193 0.189 0.250 0.202 0.159 0.239 0.267 0.282 0.227 0.279 0.332