Why is th bp increases as we move from Hcl HBr to HI

th bp of HF is the highst bcoz of its electronegativty and then it decrease at Hcl .. why it increase again from Hcl to HBr and HI

To decide the which has the highest boiling point,we have to know about the inter-molecular attractions in these compounds.(At the boiling point intermolecular attractions between liquid molecules are broken so that they become gas molecules.)Because of HF's electronegativity, it forms Hydrogen bonds between each other.But the other three do not make hydrogen bonds as the electronegativity of those halogens are not strong enough to make them.So the intermolecular attractions they have,are Van de waal bonds,which are weaker bonds when compared with hydrogen bonds.The strength of the van de waal bond increases with surface area of the molecule.The surface area increases when we move from HCl to HI.So the strength of the van de waal bonds are HCl Hope this was helpful :)