Halogens react with dihydrogen to form hydrogen halides (). Under identical conditions, what is the — Hydrogen Chemistry Question

💡 Solution & Explanation

The reactivity of halogens towards hydrogen decreases down the group. Fluorine reacts explosively even in the dark, chlorine reacts in diffused sunlight, bromine requires heating ($670\text{ K}$), and iodine requires both heating and a catalyst ($Pt$). Thus, $F_2 > Cl_2 > Br_2 > I_2$.