Question

The edge length of FCC unit cube cell is 508 pm. If the radius of cation is 110 pm, the radius of anion is ___

Answer 1

For an fcc solid, edge length, $a=2(r^{+}+r^{-})$
$\Rightarrow 2(110+r^{-})=508$
$\Rightarrow 220+2r^{-}=508$
$\Rightarrow 2r^{-}=288$
$\therefore r^{-}=144pm$