What is the coordination number of each atom in $hcp$ or $ccp$ structure?

$A$ certain metal crystallizes in a $bcc$ lattice. The distance between the nearest neighbours is $433 \text{ pm}$. The distance between the next nearest neighbours is :- .............. $\text{pm}$

How many atoms are there in a cube-based unit cell,having one atom on each corner and $2$ atoms on each body diagonal of the cube?

What is the coordination number of a particle in $fcc$ structure?

What is the coordination number of a cation occupying an octahedral void?

If three elements $X$,$Y$ and $Z$ crystallise in a $ccp$ lattice with $X$ atoms at the corners,$Y$ atoms at the cube centre and $Z$ atoms at the edges centre,the formula of the compound will be