A compound is formed hexagonal close-packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?

Correct Answer - C
To find total number of voids, we have to calculate the number of octahedral an tetrahedral voids which depend upon the number of atoms in 0.5 mole (N), so first calculate the number of atoms in 0.5 mole and then find number of octahedral voids (= N) Number of tetrahedral voids ( = 2 N ) and total voids.
Total number of atoms (N) in a closed packed structure ( 0.5 mol )
`=0.5xx6.022xx10^(23)`
`=3.11xx10^(23)`
Number of octahedral voids `=N=3.011xx10^(23)`
Number of tetrahedral voids
`=2N=2xx3.011xx10^(23)`
Total number of voids
`3.011xx10^(23)+6.022xx10^(23)`
`=9.033xx10^(23)`