Which of the following has the maximum vapour pressure?

Number of molecules from the following which can exhibit hydrogen bonding is $..........$ (nearest integer).
$CH_3OH, H_2O, C_2H_6, C_6H_6, \text{o-nitrophenol}, HF, NH_3$

The difference in the $B.P.$ of $H_2O$ $(100 \ ^oC)$ and $H_2S$ $(-42 \ ^oC)$ is explained by:

Hydrogen bonding does not play any role in the boiling of

Observe the following substances: Ethanol,acetic acid,ethylamine,trimethylamine,salicylic acid,ethanal. In the above list,the number of substances with $H$-bonding is:

Select the compound from the following that will show intramolecular hydrogen bonding.