What is the coordination number of a cation present in a tetrahedral void?

Diamond has a three-dimensional structure of $C$ atoms formed by covalent bonds. The structure of diamond has a face-centered cubic $(FCC)$ lattice where $50\,\%$ of the tetrahedral voids are also occupied by carbon atoms. The number of carbon atoms present per unit cell of diamond is $......$

What is the coordination number of $Zn$ in the crystal structure of $Zn$?

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 $Ca^{2+}$ and $F^{-}$ ions are located in $CaF_2$ crystal,respectively,at face-centered cubic lattice points and in

For an ionic crystal of the type $AB$,the value of the limiting radius ratio is $0.40$. This value suggests that the crystal structure should be: