Chemistry - Solid State Question with Solution | TestHub

Let the number of anions B in the hcp array be $N$.

The number of octahedral voids generated is equal to the number of atoms in the close-packed structure, which is $N$.

The cations A occupy $\frac{2}{3}$ of the octahedral voids.

Number of cations A = $\frac{2}{3}\times N$.

The ratio of the number of cations A to the number of anions B is $\frac{2}{3}N:N=2:3$.

The formula of the ionic compound is ${\mathrm{A}}_2{\mathrm{B}}_3$.

Answer: ${\mathrm{A}}_2{\mathrm{B}}_3$