How many atoms are there in a cubic unit cell having one atom on each corner and two atoms on each body diagonal of a cube?

In a body-centered cubic $(BCC)$ structure like $CsCl$,the distance between the two nearest neighboring spheres is equal to:

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

In a face-centered cubic $(FCC)$ arrangement,atoms $A$ are present at the corners and atoms $B$ are present at the face centers. If $4$ atoms of $A$ are removed from the corners,what is the empirical formula of the compound?

The $FCC$ crystal contains how many atoms in each unit cell?

If the radius of an anion is double that of a cation,the coordination number of the cation and the type of hole occupied are respectively: