F> CI > Br>
Which reactants will form products?

(I take it “&gt is the “>”sign). This is a very interesting question that could fill a page! Fluorine is very electronegative; and so very reactive, that in early years Platinum Setups were used instead of glass - Fluorine bonds with the Silica of Glass to yield SiF4 gas! Teflon is used today. Chlorine is very reactive, and very corrosive; I see no indication of whether these are ions, elements or what, so I am taking them to mean the Elemental forms. Bromine is likewise very reactive; but going by electronegativity and saving a page of otherwise interesting points, I will just write this; Fluorine is more reactive than Chlorine, and Chlorine is more reactive than Bromine.

As far as which is a better LEAVING group in Organic Synthesis, the order is reversed. Bromine is a good “leaving group”, Chlorine less so, and it takes a brew of Metallic Salts to remove Fluorine in Organic Synthesis.