Question

Among the following which one has the highest cation to anion size ratio ?

• A. $CsI$
• B. $CsF$
• C. $LiF$
• D. $NaF$

Answer 1

The correct option is B $CsF$

The order of size of given cations is,
$L{i}^{+}<N{a}^{+}<C{s}^{+}$
and the order of the size of given anions is,
$I^{-}>F^{-}$
Thus, when the cation is large and the anion is smallest, the cation to anion size ratio is maximum. Hence, the cation to anion size ratio is maximum for $CsF$.