Final answer:
The bond distance of BaS is greater than that of CsCl.
Step-by-step explanation:
The bond distance of BaS is greater than that of CsCl. The larger the bond distance, the lower the lattice energy. According to the provided information, the lattice energy for BaS is -3500 MJ/mol, while the lattice energy for CsCl is -657 MJ/mol. Therefore, the bond distance of BaS is greater than that of CsCl.