In a face-centered cubic unit cell,what fraction of an atom at the corner is shared by the unit cell?

$A$ 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?

$(i)$ What is meant by the term 'coordination number'?
$(ii)$ What is the coordination number of atoms:
$(a)$ in a cubic close-packed structure?
$(b)$ in a body-centred cubic structure?

What is the number of unit cells in one mole of an atom of a metal that forms a simple cubic structure?

If the radius ratio is in the range of $0.732 - 1.000$,then the coordination number will be

$A$ compound $M_pX_q$ has a cubic close packing $(ccp)$ arrangement of $X$. Its unit cell structure is shown below. The empirical formula of the compound is