Concept:The Born-Haber cycle strictly applies to the formation of ionic lattices. It models the electrostatic attraction between discrete gaseous cations (Group 1/2 metals) and anions (Halogens/Oxygen).
Solution:- We must identify the most archetypal ionic compound among the choices.
- RbBr (Rubidium Bromide) is formed from a highly electropositive Group 1 alkali metal and a highly electronegative Group 17 halogen. It forms a perfect, purely ionic lattice.
- The cycle perfectly maps the ionization of Rb and electron affinity of Br to calculate its lattice energy.
Why other options are incorrect:\( SO_2 \) and \( NH_3 \) are covalent molecules. \( PbS \) has significant covalent character and does not fit the ideal ionic Born-Haber model as cleanly as an alkali halide like RbBr.
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