# A uni-univalent ionic crystal AX is composed of the following radii (arbitrary units):$\begin{array}{1 1}A^+&X^-\\10&2.0\end{array}$.Assuming that ions are hard spheres, predict giving reasons whether the crystal will have sodium chloride or cesium chloride structure. Calculate the volume of the unit cell.

$NaCl,216(au)^3$