The enthalpy of vaporization of water is 40.7 kJ/mol, and the enthalpy of vaporization of methane, $\ce{CH4}$, is 8.2 kJ/mol. Which of the following best explains why the enthalpy of vaporization of methane is less than that of water?

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The molar mass of both molecules are similar (18 g vs 16 g). Dispersion forces typically get stronger as the mass of a molecule increases, but the two molecules have similar mass.

We aren't given the density of each compound so it would be hard to compare this.

We do know that water shows hydrogen bonding, whereas methane is nonpolar. It therefore takes more energy to separate water molecules than methane.