Chemistry - Solid State Question with Solution | TestHub

Y occupies CCP lattice hence the effective number of Y $=4$ (Effective no. of atoms in CCP is 4) X occupies $2/3$ of tetrahedral voids. Number of tetrahedral voids generated in any unit cell is $=2\mathrm{Z}$ (twice of an effective number of atoms in unit cell) $=2\times 4=8$ Since $X$ occupies $2/3$ of tetrahedral voids, so Effective number of $X=\frac{2}{3}\times 8=\frac{16}{3}$ So $X=\frac{16}{3}\&Y=4$,

Hence simplest formula is ${\mathrm{X}}_4{\mathrm{Y}}_3$