The maximum number of hydrogen bonds that a molecule of water can have is

In which of the following compounds does hydrogen bonding not play a role in its boiling point?

Hydrogen bonding is maximum in

$HCl$ is a gas,but $HF$ is a low boiling liquid. This is because

Use the information and data given below to answer the questions $(a)$ to $(c)$. Stronger intermolecular forces result in higher boiling point.
Strength of London forces increases with the number of electrons in the molecule.
Boiling points of $HF, HCl, HBr$ and $HI$ are $293 \ K, 189 \ K, 200 \ K$ and $238 \ K$ respectively.
$(a)$ Which type of intermolecular forces are present in the molecules $HF, HCl, HBr$ and $HI$?
$(b)$ Looking at the trend of boiling points of $HCl, HBr$ and $HI$,explain out of dipole-dipole interaction and London interaction,which one is predominant here.
$(c)$ Why is the boiling point of hydrogen fluoride highest while that of hydrogen chloride lowest?

The boiling points of methanol,water,and dimethyl ether are respectively $65\,^{\circ}C$,$100\,^{\circ}C$,and $-24.8\,^{\circ}C$ (note: dimethyl ether is a gas at room temperature). Which of the following best explains these wide variations in boiling point $(b.p.)$?