Question

In the zinc blende structure, $Z{n}^{2+}$ ions occupy alternate tetrahedral voids and $S^{2-}$ ions exist as $ccp$. The radii of $Z{n}^{2+}$ and $S^{2-}$ ions are $0.83\mathring{A}$ and $1.74\mathring{A}$ respectively. The edge length (in $\mathring{A}$ ) of the $ZnS$ unit cell is

Answer 1

Answer: 4.86

$r_c+r_a=\frac{a\sqrt{3}}{4}$