The number of atoms/molecules contained in one body-centered cubic unit cell is

If the side length of a face-centered cubic $(fcc)$ unit cell of a metal is $400 \ pm$, the approximate radius of the metal atom in $pm$ is $(\sqrt{2} = 1.414)$.

What is the coordination number in a hexagonal close-packed $(h.c.p.)$ structure?

In antifluorite structure,the nearest neighbour distance is $20\sqrt{3} \ pm$. Then,the edge length of the unit cell is ............... $pm$.

In the closest packed structure of a metallic lattice,the number of nearest neighbours of a metallic atom is

$A$ compound formed by elements $A$ and $B$ crystallizes in a cubic structure where $A$ atoms are at the corners of the cube and $B$ atoms are at the center of the cube. What is the formula of the compound?