Question

Select the correct statement(s) for the rock -salt structure (NaCl).

• A. The tetrahedral sites are smaller than the octahedral sites.
• B. The octahedral sites are occupied by cations and the tetrahedral sites are empty.
• C. The radius ratio, $\frac{r_{+}}{r_{-}}$ is $0.225$.
• D. The radius ratio, $\frac{r_{+}}{r_{-}}$ is $0.732$.

Answer 1

Answer: (A), (B)

The octahedral sites are occupied by cations and the tetrahedral sites are empty.
The tetrahedral sites are smaller than the octahedral sites.

The radius ratio ($r_c/r_a$) is around 0.525