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