Atoms of element $B$ form a $ccp$ lattice and atoms of element $A$ occupy $\frac{1}{2}$ of the tetrahedral voids. What is the formula of the compound formed by elements $A$ and $B$?

What is the void volume in the crystal lattice formed by a $BCC$ unit cell (in $\%$)?

In a crystalline solid with the formula $AB_2O_4$,the oxide ions are arranged in a cubic close-packed $(CCP)$ lattice,while the cations $A$ are present in tetrahedral voids and cations $B$ are present in octahedral voids. What are the percentages of tetrahedral and octahedral voids occupied by $A$ and $B$ respectively?

How will you distinguish between the following pairs of terms:
$(i)$ Hexagonal close-packing $(hcp)$ and cubic close-packing $(ccp)$?

In a close-packed arrangement,$A$ type of atoms are at corners,$B$ type of atoms are at face centers,$C$ type of atoms are at tetrahedral voids,and $D$ type of atoms are at octahedral voids. If all the atoms along any one body diagonal are removed,what will be the formula of the compound?

Atom $X$ occupies the $fcc$ lattice sites as well as alternate tetrahedral voids of the same lattice. The packing efficiency (in $\%$) of the resultant solid is closest to