When the compounds $\mathrm{HF}$, ${\mathrm{H}}_2\mathrm{O}$, ${\mathrm{NH}}_3$ , and ${\mathrm{CH}}_4$ are listed in order of increasing boiling point, which order is correct?

The size and electronegativity of the atom affect how strongly hydrogen bonds with other molecules.
A smaller atom has a higher electronegativity, which makes its H-bonding stronger. As a result, H...F>H...O>H...N is the order of H-bonding strength.
However, each HF molecule is only joined to two other HF molecules, whereas each ${\mathrm{H}}_2\mathrm{O}$  molecule forms an H-bond with four more ${\mathrm{H}}_2\mathrm{O}$ molecules.

 Order of increasing boiling point

${\mathrm{H}}_2\mathrm{O}>\mathrm{HF}>{\mathrm{NH}}_3>{\mathrm{CH}}_4$