The ionic radii of $A^{+}$ and $B^{-}$ ions are $0.98 \times 10^{-10} \ m$ and $1.81 \times 10^{-10} \ m$. The coordination number of each ion in $AB$ is.......

$A^{+}B^{-}$ shows rock salt type arrangement. Edge length of unit cell is $6 \ \mathring{A}$. If radius of $A^{+}$ is $1 \ \mathring{A}$,then the incorrect option is:

An oxide of $A$ crystallizes with $8$ atoms at the corners of the unit cell and $18$ oxygen atoms on the edges and on the faces symmetrically. What is the formula of this oxide?

The coordination number of an atom in a body-centered cubic $(BCC)$ structure is:
[Assume that the lattice is made up of atoms.]

In $CsCl$ structure,the coordination number of $Cs^{+}$ is

The coordination number in $hcp$ is