Final answer:
Al2O3 has a larger lattice energy than Al2Se3 due to the shorter interionic distance.
Step-by-step explanation:
In these two ionic compounds, the charges Z* and Z¯ are the same, so the difference in lattice energy will depend upon Ro. The O2- ion is smaller than the Se²-ion. Thus, Al2O3 would have a shorter interionic distance than Al2Se3, and Al2O3 would have the larger lattice energy.