Question

The combination of which of the following gives an ionic compound with maximum covalent character?

• A. \( \text{Mg}^{2+} \text{ and Cl}^- \)
• B. \( \text{Mg}^{2+} \text{ and O}^{2-} \)
• C. \( \text{Na}^+ \text{ and Br}^- \)
• D. \( \text{Na}^+ \text{ and O}^{2-} \)

Hint:

More charge and smaller cation + larger anion = more covalent character in ionic bonds (Fajans’ Rule).

Answer 1

The Correct Option is B

According to Fajans’ rule, covalent character in ionic bonds increases with:
- High charge on cation
- Small size of cation
- Large size and high charge on anion
Among given combinations:
- \( \text{Mg}^{2+} \) is small and highly charged
- \( \text{O}^{2-} \) is a large, doubly charged anion
Hence, \( \text{Mg}^{2+} \text{ and O}^{2-} \) forms an ionic compound with maximum covalent character.