Final answer:
The molecule that cannot form dipole-dipole forces with an identical molecule among HCl, HBr, HI, and H₂O is HI. H₂O, on the other hand, experiences strong hydrogen bonding due to its bent shape and highly electronegative oxygen.Option 3 is the correct answer.
Step-by-step explanation:
The molecule that cannot form dipole-dipole forces with an identical molecule among the given options is hydrogen iodide (HI). Molecules like HCl, HBr, and H₂O have significant differences in electronegativity between the hydrogen atom and the other atom they are bonded to, resulting in polar molecules capable of dipole-dipole interactions.
In comparison, HI also has a polar bond, but it's less polar than HCl and HBr due to the smaller electronegativity difference between hydrogen and iodine; however, it primarily exhibits London dispersion forces due to its larger size and more electrons compared to HCl and HBr. In contrast, H₂O has a significant dipole moment due to its bent shape and the presence of hydrogen bonding, which is a special type of dipole-dipole interaction.