The edge length of a face centred unit cubic cell is $508 \mathrm{pm}$. If the radius of the cation is $110 \mathrm{pm}$ the radius of the anion is

The relation between the radius of cation and anion, in fcc unit cell, can be mathematically represented as $r_c+r_a=\frac{a}{2}$

Substituting provided values in the equation and solving we get,

$110+r_a=\frac{508}{2}$

$\therefore {\mathrm{r}}_{\mathrm{a}}=144\mathrm{pm}$

Therefore, the correct answer is C).