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

If three elements $A, B, C$ crystallize in a cubic solid lattice with $B$ atoms at the cubic centers, $C$ atoms at the center of edges, and $A$ atoms at the corners, then the formula of the compound is

The number of close neighbours in a body-centred cubic $(BCC)$ lattice of identical spheres is:

In an ionic crystal with the general formula $AX$,if the coordination number is $6$,what will be the value of the radius ratio?

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?

The volume occupied by all the particles in a $B.C.C.$ unit cell is