In a simple cubic unit cell,how many unit cells share each lattice point located at the corner?

The coordination number of a hexagonal close-packed $(hcp)$ crystal structure is......

$A$ cubic solid is made of two elements $P$ and $Q$. Atoms of $Q$ are at the corners of the cube and $P$ at the body-centre. What is the formula of the compound? What are the coordination numbers of $P$ and $Q$?

In sodium chloride crystal,the number of next nearest neighbours of each $Na^{+}$ ion is

If the coordination number of $Ca^{2+}$ in $CaF_2$ is $8$,then the coordination number of $F^{-}$ ion would be

In an $fcc$ crystal lattice,atoms $A$ are present at the corners and atoms $B$ are present at the face centers. If one atom $A$ is missing from a corner,what is the molecular formula of the compound?