Can you help me with the question: "State and explain the trend in boiling temperature of hydrogen halides down the group"?

So the trend is a high boiling point for HF, then a sharp decease to HCl, and then a steady increase up to HI. HF is a special case because they are held together by hydrogen bonds (as well as permanent dipole-dipole interactions and London forces) whereas HCl, HBr, and HI have 'minimal' hydrogen bonding (I purposely chose not say no Hydrogen bonding as they do exhibit minimal degrees of hydrogen bonding but to an insignificant level, so it's technically incorrect to say they have none). Also, remember that we are looking at INTERmolecular forces, not INTRAmolecular forces when considering boiling point. HF can form hydrogen bonds due to fluorine's high electronegativity. Because the difference in electronegativity between hydrogen and fluorine is so great (Fluorine has the highest electronegativity), HF can form strong hydrogen bonds that require higher energies (and hence temperature) to break, resulting in a high boiling point. HCl, HBr, and HI form London forces which are much weaker and easier to break, resulting in a much lower boiling point. However, the boiling point increases as you go from HCl to HI. This is due to the increased number of electrons. More electrons means greater London forces due to increased fluctuation in electron density. Hence, there is a greater electrostatic attraction between molecules as you go from HCl to HI since the number of electrons per molecule increases.