A compound forms a hexagonal close-packed structure. What is the total number of voids in 0.5 \mathrm{~mol} of it? How many of these are tetrahedral voids?
A compound forms a hexagonal close-packed structure. What is the total number of voids in 0.5 \mathrm{~mol} of it? How many of these are tetrahedral voids?

A compound is formed by two elements \mathrm{M} and \mathrm{N}. The element \mathrm{N} forms ccp and atoms of M occupy 1 / 3 r d of tetrahedral voids. What is the formula of the compound?