According to Fajans'rules, the percentage of covalent character in an ionic compound increase if the cation is highly charged or small in size and the anion is large or cation has pseudoinert gas configuration. As a result of the increased covalent character, solubility in less polar solvent increases and the melting point decreases.
The correct order of increasing ionic character is

Options

A. `BeCl_2 lt MgCl_2 lt CaCl_2 lt BaCl_2`
B. `BeCl_2 lt MgCl_2 lt BaCl_2 lt CaCl_2`
C. `BeCl_2 lt BaCl_2 lt MgCl_2 lt CaCl_2`
D. `BaCl_2 lt MgCl_2 lt CaCl_2 lt BeCl_2`

Answer

A

Explanation

According to Fajan's rule as size of cations increase, their polarising power decreases and thus ionic character increase.So option A is correct.