Which is the weakest among the following types of bond?

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

Viscosity of a liquid arises due to strong intermolecular forces existing between the molecules. Stronger the intermolecular forces,greater is the viscosity. Name the intermolecular forces existing in the following liquids and arrange them in the increasing order of their viscosities. Also give reason for the assigned order in one line.
Water,hexane $(CH_3CH_2CH_2CH_2CH_2CH_3)$,glycerine $(CH_2OHCH(OH)CH_2OH)$

Which one of the halogen acids is a liquid at room temperature?

Which of the following molecules can form hydrogen bonding with itself?

Assertion : Molar enthalpy of vaporisation of water is different from ethanol.
Reason : Water is more polar than ethanol.