Question

Which of the following compounds has maximum covalent character?

• A. \(\text{LiCl}\)
• B. \(\text{LiI}\)
• C. \(\text{NaCl}\)
• D. \(\text{NaI}\)

Hint:

To find maximum covalent character: Choose \textbf{small cation + large anion}. Order of anion size: \(\text{I}^->\text{Br}^->\text{Cl}^->\text{F}^-\)

Answer 1

The Correct Option is B

Concept:
According to Fajans' Rule, covalent character increases when:

• Cation is small and highly polarizing
• Anion is large and highly polarizable

Step 1: Compare cations. \[ \text{Li}^+ \text{ is smaller than } \text{Na}^+ \] So, \(\text{Li}^+\) has higher polarizing power.
Step 2: Compare anions. \[ \text{I}^->\text{Cl}^- \text{ (size)} \] So, \(\text{I}^-\) is more polarizable.
Step 3: Apply Fajans' Rule. Maximum covalent character occurs when: \[ \text{Small cation + Large anion} \] Thus: \[ \text{LiI} \text{ has highest covalent character} \]
Step 4: Conclusion. \[ {\text{LiI is most covalent}} \]