Among the following, the one which has maximum ionic character is

Concept:

 According to Fajan's rule:

• The smaller the cation, the bigger the anion, and the more the covalent character.
• Bigger cations and smaller anions will favor ionic character.

Explanation:

In the given options all have the same anion (Cl^-), the character of the compounds decided by cation only.

Na, K, Li, and Cs belong to I group and their order of atomic size is:

Li < Na < K < Cs.

According to Fajan's rule: Bigger cations and smaller anions will favor ionic character.

So, CsCl has maximum ionic character.