The number of octahedral sites per sphere in a $fcc$ structure is

Gold has a face-centred cubic $(fcc)$ lattice with an edge length of the unit cube of $407 \ pm$. Assuming the closest packing, the diameter of the gold atom is .............. $pm$.

If $a$ is the length of the side of a cube,the distance between the body-centered atom and one corner atom in the cube will be

What is the coordination number of the $Ca^{2+}$ ion in the fluorite structure?

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

The number of spheres contained $(i)$ in one body centred cubic unit cell and $(ii)$ in one face centred cubic unit cell,is