Chemistry - Solid State Question with Solution | TestHub

Let the number of anions (A) forming the hexagonal closest packing be $N$.

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

Since cations (C) occupy $2/3$ of the octahedral voids, the number of cations (C) is $\frac{2}{3}N$.

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

The general formula of the compound is ${\text{C}}_2{\text{A}}_3$.

Answer: ${\text{C}}_2{\text{A}}_3$