Which one of the following has minimum value of size of cation/anion ratio ?

Options

A. `NaCI`
B. `KCI`
C. `MgC1_(2)`
D. `CaF_(2)`

Answer

C

Explanation

On moving down a group ionic radius increases .
Thus `Na^(+)` has smaller radius than `K^(+)` and `Mg^(2+)` has smaller radius than `Ca^(2+)`.
In contrast on moving across a period , ionic radius decreases .Thus `Mg^(2+)` has smaller radius than `Ca^(2+)` .In other words `Mg^(2+)` has the smallest radius amongst `Na^(+) , K^(+) , Mg^(2+) ` and `Ca^(2+)`
Amongst halogens `C1^(-)` has lergest radius than `F^(-)`. thus `MgC1_(2)` has the smallest ratio of the size of cation to anion.