In a face-centered cubic $(FCC)$ unit cell,how many unit cells share an atom located at the face center?

In a hexagonal close packing $(hcp)$ lattice,each sphere touches ................... spheres in its own layer.

In metallic solids,the number of atoms for the face-centered and the body-centered cubic unit cells are,respectively:

The correct coordination number for the zinc ion in the zinc blende crystal structure is:

What is the radius ratio $r^+/r^-$ for $NaCl$?

$A$ cubic structure is formed where atoms of element $X$ are occupied at the corners of the cube and also at the face centers. Atoms of element $Y$ are present at the body center and at the edge centers. If all the atoms are removed along a plane passing through the middle of the cube (bisecting the four edges), the formula will become