Question

Which of the follownig is/are examples of polar molecular solids?

• A. $HCl\left(s\right)$
• B. $S{O}_2\left(s\right)$
• C. $N{H}_3\left(s\right)$
• D. $NaCl\left(s\right)$

Answer 1

Answer: (A), (B), (C)

$N{H}_3\left(s\right)$

Polar Molecular solids :
The molecules of substances like $HCl\left(s\right),S{O}_2\left(s\right),N{H}_3\left(s\right)$are formed by polar covalent bonds.
The molecules in such solids are held together by relatively stronger dipole-dipole interactions. These solids are soft and non-conductors of electricity.
Their melting points are higher than those of non polar molecular solids yet most of these are gases or liquids under room temperature and pressure.
Example :
Dipole-Dipole interactions in $HCl$

Option (d) :
$NaCl\left(s\right)$ is an example of ionic solid, which has coulombic force of attraction