Question

The ionic radii of $C{a}^{2+}$ and $F^{-}$ are 100 pm and 133 pm respectively. The coordination number of $C{a}^{2+}$ in the ionic solid will be

• A. 8
• B. 6
• C. 4
• D. 2

Answer 1

Answer: (A)

Radius $ratio=\frac{r_{C{a}^{2+}}}{r^{F-}}=\frac{100pm}{133pm}=0.75$ As, $\text{0}\text{.73}\frac{{\text{r}}_{\text{cation}}}{{\text{r}}_{\text{anion}}}.$ So, coordination number of cation = 8