What type of intermolecular or intramolecular forces are present in ethylene glycol?

Among $H_2O, H_2S, H_2Se$ and $H_2Te$,the substance with the highest boiling point is,

The boiling point of hydrogen halides varies in the order:

Structures of molecules of two compounds are given below:
$(a)$ Which of the two compounds will have intermolecular hydrogen bonding and which compound is expected to show intramolecular hydrogen bonding.
$(b)$ The melting point of a compound depends on,among other things,the extent of hydrogen bonding. On this basis,explain which of the above two compounds will show a higher melting point.
$(c)$ Solubility of compounds in water depends on the power to form hydrogen bonds with water. Which of the above compounds will form hydrogen bonds with water easily and be more soluble in it?

Acetic acid exists as a dimer in benzene due to

Hydrogen bonding does not play a central role in the following phenomena: