How many next nearest neighbours are present for ${\text{Zn}}^{+2}$  ions in FCC arrangement of  $\text{ZnS.}$

Next nearest neighbour of $Z{n}^{+2}$  would be = no of nearest surrounded  $Z{n}^{2+}$ ions
next nearest neighbour of  $s^{2-}$ would be = no of nearest  $s^{2-}$ ions  $=12\left(\text{due\hspace{0.17em}\hspace{0.17em}to\hspace{0.17em}\hspace{0.17em}FCC}\right)$
and their number of neighbour ratio is 1:1 and that make  $Z{n}^{2+}$ neighbour are 12.