Question

If the limiting radius ratio $\left(\frac{r^{+}}{r^{-}}\right)$is the range of $0.225$ to $0.414$, there is :
(1) tetrahedral voids
(2) co-ordination number $4$
(3) zinc blende structure
(4) $NaCl$ type structure

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (A)

ZnS (zinc blende) has a co-ordination number $4.$
Its arrangement is tetrahedral and limiting radius ratio $\left(r^{+}/r^{-}\right)$is in the range of $0.225$ to $0.414$