What type of crystal structure from the following has $52.36 \%$ packing efficiency?

In a compound formed by atoms $A$ and $B$, atoms $A$ form a cubic close-packed $(CCP)$ structure, while atoms $B$ are located at the center of each edge. If the edge length of the cubic unit cell is $115 \ pm$, the distance of atom $A$ from the center of the cube is .......... $pm$.

In a solid compound,the atoms of $A$ form a face-centered cubic $(fcc)$ lattice,while atoms of $B$ occupy all octahedral voids and half of the tetrahedral voids. The molecular formula of the solid will be ........

Calculate the number and position of tetrahedral and octahedral voids in a $ccp$ or $fcc$ structure.

In a cubic close-packed $(ccp)$ structure,if there are $N$ spheres,what is the number of octahedral voids?

Which of the following statements is $NOT$ correct regarding voids in lattice structure?