Calculate the volume of $fcc$ unit cell in $cm^3$ if void volume of it is $4.16 \times 10^{-24} \ cm^3$.

The molecular formula of a crystalline solid is $X_3Y_2$. Atoms of $Y$ form $ccp$ lattice,and atoms of $X$ occupy $50\%$ octahedral voids and $x\%$ of tetrahedral voids. What is the percentage of unoccupied tetrahedral voids?

$A$ metal oxide crystallises in a hexagonal close-packed $(HCP)$ array of oxide ions with two out of every three octahedral holes occupied by metal ions. The formula of the metal oxide is:

In crystalline silicon,$Si$ atoms occupy all the $ccp$ sites and every alternate tetrahedral void. The value of packing efficiency is closest to $....\%$

$A$ face-centred cubic $(FCC)$ unit cell is made up of two types of atoms $A$ and $B$,in which $A$ occupies the corner positions and $B$ occupies the face centres. If atoms along one of the body diagonals are removed,what is the empirical formula of the remaining solid?

Calculate the packing efficiency in a metal crystal for a face-centred cubic $(FCC)$ unit cell (assuming that atoms are touching each other).