An $AB_2$ type structure is found in

Which of the following statements is incorrect for the rock salt type structure?

What is the total volume occupied by atoms in a face-centered cubic $(FCC)$ unit cell of a metal?

$CsBr$ crystal has $bcc$ structure. It has an edge length of $4.3 \ \mathring{A}$. The shortest interionic distance between $Cs^{+}$ and $Br^{-}$ ions is ................ $\mathring{A}$.

For tetrahedral coordination number,the radius ratio $\frac{r_{c^+}}{r_{a^-}}$ is

The coordination number of $Na^{+}$ in $NaCl$ is