Question

Which of the following orders of ionic radii is correctly represented?

• A. $H^{-}>H>H^{+}$
• B. $\text{A}\text{l}^{3 +}>\text{M}\text{g}^{2 +}>N^{3 -}$
• C. $F^{-}>O^{2 -}>\text{N}\text{a}^{+}$
• D. $\text{N}\text{a}^{+}>F^{-}>O^{2 -}$

Answer 1

Answer: (A)

As size $ \propto \frac{e}{p}$ ratio for ions.
Size of anion > size of atom > size of cation
$H^{-}>H>H^{+}$
In case of $F^{-},O^{- 2},Na^{+}$
radii order is $O^{- 2}>F^{-}>Na^{+}$
correct order for $Al^{+ 3},Mg^{+ 2},N^{- 3}$ is $N^{- 3}>Mg^{+}>Al^{+ 3}$