Question

The correct sequence of increasing covalent character is represented by:

• A. $LiCl<NaCl<BeC{l}_2$
• B. $BeC{l}_2<LiCl<NaCl$
• C. $NaCl<LiCl<BeC{l}_2$
• D. $BeC{l}_2<NaCl<LiCl$

Answer 1

The correct option is C $NaCl<LiCl<BeC{l}_2$

Covalent character in an ionic compound is predicted by Fajan's rule.
According to Fajan's rule:
(i) Greater the size of the cation, lesser will be its polarizing power and lesser will be the covalent character.
(ii) Greater the size of anion, greater will be its polarizability and greater will be the covalent character.
(iii) Greater the charge on the cation and anion, more will be its polarizing power and polarizability respectively and therefore more will be its covalent character.

The size of cations increases in the order
$B{e}^{2+}<L{i}^{+}<N{a}^{+}$

Hence, $BeC{l}_2>LiCl>NaCl$ (Covalent character)