The hydrogen bond is not present in

The boiling point of glycerol is higher than that of propanol because of:

Hydrogen bonding plays a central role in the following phenomena:
$(A)$ Ice floats in water.
$(B)$ Higher Lewis basicity of primary amines than tertiary amines in aqueous solutions.
$(C)$ Formic acid is more acidic than acetic acid.
$(D)$ Dimerisation of acetic acid in benzene.

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

Which of the following has the maximum vapour pressure?

The hydrogen bond strength will be highest for