Which type of cubic lattice has the maximum number of atoms per unit cell?

In the crystal of $CsCl$,the nearest neighbours of each $Cs^+$ ion are

The vacant space in the $bcc$ unit cell is .............. $\%$

In a $bcc$ unit cell,what is the number of atoms per unit cell?

The correct coordination number for the zinc ion in the zinc blende crystal structure is:

In a face-centred cubic $(FCC)$ lattice,atoms of $A$ form the corner points and atoms of $B$ form the face-centred points. If two atoms of $A$ are missing from the corner points,the formula of the ionic compound is