🤓 Based on our data, we think this question is relevant for Professor Bezabeh's class at University of Guam.

- At conditions of high pressure, RbI will appear to have a similar structure like CsCl.
- CsCl is known to have a body centered cubic structure
- Ionic radius of rubidium and iodide ions are 1.52 Å and 2.20 Å
- Body diagonal of a BCC structure is composed of 4 radii of the atoms (2 radii of each ion)
- Based on the Pythagorean theorem, edge length can be calculated using the formula:

At room temperature and pressure RbI crystallizes with the NaCl-type structure.

At high pressure the structure transforms to one with a CsCl-type structure. Use ionic radii to predict the length of the cubic unit cell edge for the high-pressure form of RbI. Radius of Rb^{+ }is 1.52 Å and I^{- }is 2.20 Å