A solid has a structure in which ' W ' atoms are located at the corners of a cubic lattice, oxygen atoms at the edge centre and

Na atom at the body centre. The formula of the compound is

KBr has rock salt type structural arrangements and has a density of

$3.70 \mathrm{~g} / \mathrm{cm}^3$. The edge length of the unit cell is approximately [molecular weight of $\mathrm{KBr}=120 \mathrm{~g} / \mathrm{mol}$ ]

If the length of the body diagonal of a FCC unit cell is $x \mathop {\rm{A}}\limits^{\rm{o}}$, the distance between two octahedral voids in the cell in $\mathop {\rm{A}}\limits^{\rm{o}}$ is

The number of nearest neighbours in a bcc unit cell is