Rubidium iodide crystallizes with a cubic unit cell that contains iodide ions at the corners and a rubidium ion in the center. What is the formula of the compound?

RbI

Explanation:

The formula of a compound can be obtained on the basis of number of anion and cations in the unit cell. Iodide is present at the eight corners of the cubic cell.

So, no. of iodide ion = 1/8*8 = 1

rubidium is present at the center

so, no. of rubidium ion = 1*1 = 1

Therefore formula of the compound = RbI