Which of the following molecules has intramolecular hydrogen bonding?

$NH_3$ has a much higher boiling point than $PH_3$ because

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 $(b.p.)$?

Explain: Hydrogen Bond and Thermal Energy.

Which compound forms a linear polymer due to $H$-bonding?

The number of $H_2O$ molecules participating in hydrogen bonding in $CuSO_4 \cdot 5H_2O$ is/are