Question

Which of the following pairs of elements forms a compound with maximum ionic character?

• A. $Na$ and $F$
• B. $Cs$ and $F$
• C. Na and C
• D. $Cs$ and $I$

Answer 1

The correct option is B $Cs$ and $F$

According to fajan's rule, more the polarization of an anion by the cation, more will be the covalent character in the ionic bond. For maximum ionic character, the polarization of the anion by the cation should be small i.e. size of cation should be large and size of anion should be small. Therefore, the compound formed by $Cs$ and $F$ will have the maximum ionic charcter.