Which of the following forms a dimer by $H$-bond?

In which of the following is intramolecular $H$-bonding absent?

When two ice cubes are pressed together,they join to form a single cube. Which of the following forces is responsible for holding them together?

Use the information and data given below to answer the questions $(a)$ to $(c)$. Stronger intermolecular forces result in higher boiling point.
Strength of London forces increases with the number of electrons in the molecule.
Boiling points of $HF, HCl, HBr$ and $HI$ are $293 \ K, 189 \ K, 200 \ K$ and $238 \ K$ respectively.
$(a)$ Which type of intermolecular forces are present in the molecules $HF, HCl, HBr$ and $HI$?
$(b)$ Looking at the trend of boiling points of $HCl, HBr$ and $HI$,explain out of dipole-dipole interaction and London interaction,which one is predominant here.
$(c)$ Why is the boiling point of hydrogen fluoride highest while that of hydrogen chloride lowest?

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

The crystal lattice of ice is mostly formed by