The freezing point of helium is approximately -270°C. The freezing point of xenon is -112°C. Both of these are in the noble gas family. Which of the following statements is supported by these data?
A) Helium and xenon form highly polar molecules.
B) As the molar mass of the noble gas increases, the freezing point decreases.
C) The London forces between the helium molecules are greater than the London forces between the xenon molecules.
D) The London forces between the helium molecules are less than the London forces between the xenon molecules.
E) none of these

Question

Quizplus · Accepted Answer

The freezing point of a substance is generally determined by the strength of intermolecular forces present between molecules. As the size of the noble gas atom increases, so do the number of electrons, making the dispersion forces (London forces) stronger. Therefore, the London forces between xenon molecules would be greater than the London forces between helium molecules. So, the correct statement is D.

The Freezing Point of Helium Is Approximately -270°C