What is the coordination number of a sphere in a simple cubic lattice?

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

The tetrahedral voids formed by $ccp$ arrangement of $Cl^{-}$ ions in rock salt structure are

$A$ compound having elements $X$ and $Y$ crystallises in a cubic structure, where $X$ is at the corner position and $Y$ is at the center of the cube. The correct formula of the compound is

How many atoms are there in a cubic unit cell having one atom on each corner and two atoms on each body diagonal of a cube?

What is the coordination number of $Cu$ in a face-centered cubic $(fcc)$ lattice?