What is a common property shared by all halogens?

Halogens, which include elements such as fluorine, chlorine, bromine, iodine, and astatine, are known for their ability to react with metals to form ionic compounds called salts. This property is a defining characteristic of halogens. When a halogen interacts with a metal, it typically gains an electron to achieve a more stable electron configuration, leading to the formation of a halide ion and a metal cation, resulting in the formation of a salt.

The tendency to form salts is fundamental to the chemical behavior of halogens and is a primary reason for their classification in Group 17 of the periodic table. The other options do not accurately describe halogens: they are not stable and unreactive (as they are highly reactive), they are not located in Group 1 (that group contains alkali metals), and they do not have similar boiling points—boiling points vary significantly among them due to increasing molecular weight and van der Waals forces. Thus, the correct choice demonstrates a crucial and well-known aspect of halogen chemistry.