Final answer:
The compounds can be arranged in order of increasing lattice energy as CsI < NaF < CaO.
Step-by-step explanation:
The lattice energy is a measure of the stability of an ionic compound. It is directly proportional to the product of the ionic charges and inversely proportional to the internuclear distance. In the given compounds, the ionic charges are:
- NaF: Na+ and F-
- CsI: Cs+ and I-
- CaO: Ca2+ and O2-
Based on the trend mentioned in the information provided, the larger the ionic charges, the higher the lattice energy. So, we can arrange the compounds in order of increasing lattice energy as:
CsI < NaF < CaO