Chemistry - Solid State Question with Solution | TestHub

In a ccp structure, the number of ${\mathrm{B}}^{-}$ ions per unit cell is calculated from the corners and face centers:

Number of ${\mathrm{B}}^{-}$ ions = $8\times \frac{1}{8}+6\times \frac{1}{2}=1+3=4$

The number of tetrahedral voids in a ccp structure is twice the number of atoms per unit cell, which is $2\times 4=8$.

Since ${\mathrm{A}}^{+}$ ions occupy half of the tetrahedral voids:

Number of ${\mathrm{A}}^{+}$ ions = $\frac{1}{2}\times 8=4$

The ratio of ${\mathrm{A}}^{+}$ to ${\mathrm{B}}^{-}$ is $4:4$, which simplifies to $1:1$.

Therefore, the formula of the solid is AB.

Answer: AB