Question

Which of the following is a distinguishing feature between a polar and a non-polar compound?

• A. Polar compounds generally ionize in water.
• B. Polar compounds generally exist in liquid or gaseous state.
• C. Polar compounds do not conduct electricity in the pure form.
• D. Intermolecular forces of attraction are weak in polar compounds

Answer 1

The correct option is A

Polar compounds generally ionize in water.

Explanation of correct option:

• Polar compounds generally ionize in water.
• Consider the example of Sodium chloride ($\mathrm{NaCl}$), when it is added to water it breaks into ${\mathrm{Na}}^{+}$ and ${\mathrm{Cl}}^{-}$.
• Water (${\mathrm{H}}_2\mathrm{O}$) itself is polar.
• Since oxygen is more electronegative than hydrogen, the electrons remain shifted toward the oxygen atom giving it a partial negative charge.
• Now in presence of this partially charge-separated water molecule when $\mathrm{NaCl}$ is added water interacts with $\mathrm{NaCl}$.
• The oxygen atoms attract the ${\mathrm{Na}}^{+}$ ion while the hydrogen atoms in water interact with the ${\mathrm{Cl}}^{-}$ion, which leads to the separation of $\mathrm{NaCl}$.

Explanation of incorrect options:

(B) Polar compounds generally exist in the liquid or gaseous state.

Non-polar compounds can also exist in the liquid or gaseous states. Like ${\mathrm{H}}_2,{\mathrm{Cl}}_2,{\mathrm{N}}_2$, all are non-polar gas.

(C) Polar compounds do not conduct electricity in their pure form.

Non-polar compounds when in pure form do not conduct electricity.

(D) Intermolecular forces of attraction are weak in polar compounds.

In non-polar compounds like ${\mathrm{H}}_2$, London forces are operational, which is a weaker Van der Waal force.

Hence, the correct option is (A).