The number of octahedral voids in a unit cell of a cubical closest packed structure is

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

The coordination number of the sphere in cubic close packed $(ccp)$ structure is

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

$CsCl$ crystallises in a body-centred cubic $(BCC)$ lattice. If '$a$' is its edge length,then which of the following expressions is correct?

$A$ compound is formed by elements $A$ and $B$. Atoms of $A$ are present at the corners of the cube,and atoms of $B$ are present at the body center. What is the formula of the compound?