Final answer:
Fluorine has the lowest boiling point among the halogens because it is the smallest and lightest halogen molecule, experiencing the weakest dispersion forces.
Step-by-step explanation:
The halogen with the lowest boiling point is expected to be the one with the weakest intermolecular forces. Among the options given, Fluorine (F₂), Chlorine (Cl₂), Bromine (Br₂), and Iodine (I₂), the trend in intermolecular forces is related to the size and mass of the molecules. Larger and heavier molecules, like Iodine, experience stronger London dispersion forces, increasing their boiling points.
Fluorine and Chlorine, being lighter and smaller, experience weaker dispersion forces than heavier molecules like Bromine and Iodine. Fluorine, being the smallest and lightest halogen molecule, has the weakest dispersion forces and therefore has the lowest boiling point.
Thus, the halogen with the lowest boiling point would be Fluorine (Option A).