The $8:8$ type packing is present in which of the following?

$A$ binary compound $(A^{+} B^{-})$ has a zinc blende structure where $B^{-}$ ions form the lattice and $A^{+}$ ions occupy $25\%$ of the tetrahedral voids. What is the formula of the compound?

The arrangement of $X^{-}$ ions around $A^{+}$ ion in solid $AX$ is given in the figure. If the radius of $X^{-}$ is $250 \ pm$, the radius of $A^{+}$ is: (in $pm$)

The radius of a calcium ion is $94 \text{ pm}$ and of the oxide ion is $146 \text{ pm}$. The possible crystal structure of calcium oxide will be

In $FCC$ lattice,alternate tetrahedral voids are occupied in which of the following?

In $NaCl$ type structure, the shortest distance between two nearest neighbours is $100 \ pm$. Then, the distance between two next nearest neighbours in the same unit cell will be: