Question

The incorrect order of melting points among the following is:

• A. $NaCl>LiCl$
• B. $LiCl>NaCl$
• C. $NaCl>KCl$
• D. $KCl>LiCl$

Answer 1

The correct option is B $LiCl>NaCl$

As we move down the group, lattice energy decreases and hence the melting point decreases. However, LiCl has some covalent character due to the polarization of $C{l}^{-}$ by $L{i}^{+}$. Hence, it has lower melting point.
Hence, the correct order of melting points of the given alkali metal chlorides is
$NaCl>KCl>LiCl$.