Question

How many octahedral voids are there in $1$ mole of an element having cubic close packed structure?

Answer 1

In an unit cell effectively $4$ octahedral voids are present. In a unit cell $4$ atoms of elements are present effectively.

Total no. of unit cells $=\frac{1\times 6.023\times {10}^{23}}{4}$

Total no. of octahedral voids $=\frac{6.023\times {10}^{23}}{4}\times 4=6.023\times {10}^{23}$