In a hexagonal close-packed $(HCP)$ structure,the third layer covers the ........ holes created between the first and second layers.

In a close-packed lattice,the number of tetrahedral voids compared to the number of octahedral voids is:

$A$ mineral consists of a cubic close-packed structure formed by $O^{2-}$ ions,where half the octahedral voids are occupied by $Al^{3+}$ and one-eighth of the tetrahedral voids are occupied by $Mn^{2+}$. The chemical formula of the mineral is

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

The stacking pattern in a body-centered cubic $(bcc)$ lattice is of the type............

If $0.5 \ mol$ of a metal forms a hexagonal close-packed structure,the total number of voids and tetrahedral voids respectively in $mol$ are