The hydrogen bond is strongest in

The boiling point of hydrogen halides varies in the order:

The compound/s which will show significant intermolecular $H$-bonding is/are :
$(a)$ $o$-Nitrophenol
$(b)$ $N$-($4$-hydroxyphenyl)acetamide
$(c)$ $2,6$-di-tert-butylphenol

At room temperature $H_2O$ is a liquid while $H_2S$ is a gas. The reason is

The hydrogen bond strength will be highest for

In ice,the $H - O - H$ bond angle is closest to which of the following?