If the number of atoms per unit cell in a crystal is $2$,the structure of the crystal is:

In the structure of a solid, $W$ atoms are located at the cube corners of the unit cell, $O$ atoms are located at the cube edges, and $Na$ atoms are at the cube centers. The formula of the compound is:

The structure of $Na_2O$ crystal is

The number of octahedral voids per lattice site in a lattice is $...$ (Rounded off to the nearest integer).

In which of the following crystals are alternate tetrahedral voids occupied?

For an ionic crystal of the general formula $AX$ and coordination number $6$,the value of radius ratio will be