Question

At first glance, it would seem that carbon tetrafluoride $\left(C{F}_4\right)$ should be very similar to carbon tetrachloride $\left(CC{l}_4\right)$. Their names and their formulas are very similar.
However, these molecules have different boiling points. The boiling point of $C{F}_4$ is $145K$, and the boiling point of $CC{l}_4$ is $350K$.
Which of the following statements is the best explanation for this difference in boiling point?

• A. The carbon tetrachloride molecule is larger and more polarized than the carbon tetrafluoride molecule.
• B. The $C-Cl$ bond is stronger and harder to break than the $C-F$ bond.
• C. Fluorine is more electronegative than chlorine, so the $C-F$ bond is more polar than the $C-Cl$ bond.
• D. Carbon tetrachloride has dipole-dipole forces, whereas carbon tetrafluoride only has London dispersion forces.

Answer 1

Answer: (A)

The carbon tetrachloride molecule is larger and more polarized than the carbon tetrafluoride molecule.

The $e^{-}s$ that are away from the nucleus can rearrange themselves more easily, hence are more polarizable, this is the reason due to which $CC{l}_4$ is having a higher boiling point than $C{F}_4$, also it is due to the greater London dispersion forces.

Hence, option A is correct.