Which halogen is most likely to react?

a. Br (bromine)

b. F (fluorine)

c. I (iodine)

d. Cl (chlorine)

The correct answer is B. Fluorine is the most reactive among the choices. The choices given belongs to the group of halogens which means salt-producing. These elements reacts with metals to produce salts. The reactivity of these halogens can be predicted using the periodic table. As you go down the group 7 elements, reactivity of these elements decreases.