Question

If the radius of the anion in an ionic solid is $200$ pm, what would be the radius of the cation that fits exactly into a cubic hole?

• A. $146.4$pm
• B. $82.8$pm
• C. $45$pm
• D. None of these

Answer 1

The correct option is A $146.4$pm

For cubic hole the radius ratio of cation by anion ranges from $0.732-1$

$\frac{r^{+}}{r^{-}}=0.732$ for cubic holes.

$\therefore r^{+}=200\times 0.732$

$=146.4pm$

Hence, the correct option is A.