Final answer:
Rubidium iodide has a body-centered cubic structure, with one iodide ion at each corner of the unit cell and one rubidium ion in the center. Each corner ion is shared by eight unit cells, leading to a 1:1 ratio of rubidium to iodide ions and the formula RbI. Option a
Step-by-step explanation:
The question involves determining the formula of a compound based on its crystalline structure. Rubidium iodide forms a cubic unit cell with iodide ions at the corners and a rubidium ion at the center. This indicates the structure is similar to a body-centered cubic (BCC) lattice structure.
In a cubic unit cell, each corner atom is shared by eight adjacent unit cells, so each corner contributes 1/8 of an ion to the unit cell. Since there are eight corners, the total contribution of iodide ions is 8 * 1/8 = 1 iodide ion (I-). There is one rubidium ion (Rb+) at the center of the unit cell, and it belongs entirely to the unit cell. Therefore, the ratio of rubidium ions to iodide ions is 1:1, yielding the empirical formula RbI for rubidium iodide. Option a