Question

Which of the following is most covalent among the given four ionic solids?

• A. $NaCl$
• B. $KCl$
• C. $RbCl$
• D. $CsCl$

Answer 1

The correct option is A $NaCl$

According to Fajans' rule, for same anion, more is the polarising power of the cation, more is the covalent character. Here, we are considering only the alkali metals, and since the size of $N{a}^{+}$ ion is the smallest so, it has highest polarising power. Hence, $NaCl$ is the most covalent molecule.