In $FCC$,the distance between the nearest tetrahedral voids is:

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

$A$ body-centred cubic $(BCC)$ lattice is made up of two different types of atoms $X$ and $Y$. Atom $X$ occupies the body centre and atoms $Y$ occupy the corner positions. One of the corners is left unoccupied per unit cell. The empirical formula of it is

$A$ compound is formed by two elements $X$ and $Y$. Atoms of the element $Y$ (as anions) make $ccp$ and those of the element $X$ (as cations) occupy all the octahedral voids. What is 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

Calculate the packing efficiency in a body-centred cubic $(BCC)$ structure.