A solid binary compound XY has the Rock Salt () structure. If the radius of the cation is exactly , — Solid State Chemistry Question

💡 Solution & Explanation

In the rock salt structure, the cation occupies an octahedral void, so the minimum stable ratio is $r_+/r_-=0.414$. Thus $r_- = \frac{r_+}{0.414}=\frac{100}{0.414}\text{ pm}\approx241.5\text{ pm}$.