The percentage of vacant space for $bcc$ unit cell is ............. $\%$

What are the number of octahedral and tetrahedral voids in $0.3 \ mol$ of a substance respectively,if it forms an $hcp$ structure?

$A$ solid is made of two elements $X$ and $Y$. Atoms of $X$ are in $FCC$ arrangement and $Y$ atoms occupy all tetrahedral sites. What is the possible formula of the compound?

Explain three-dimensional close packing from two-dimensional hexagonal close packing. Explain the formation of face-centered cubic $(FCC)$ unit cell and hexagonal close packing $(HCP)$ in three dimensions.

If $AB$ crystallizes in a zinc blende structure with $B^{-}$ ions at lattice points,what fraction of tetrahedral voids is occupied by $A^{+}$ ions? ............... $\%$

How many unit cells share a corner of a unit cell in a crystal lattice?