The density of water is higher than that of ice due to:

The boiling point of a compound is raised by

The hydrogen bond is strongest in

Intramolecular hydrogen bonding is formed in

Which of the following molecules are expected to exhibit intermolecular $H$-bonding?
$(I)$ Acetic acid $(II)$ $o$-nitrophenol $(III)$ $m$-nitrophenol $(IV)$ $o$-boric acid
Select the correct alternative.

The boiling point of water is higher than that of liquid $HF$. The reason is that