Question

which element is likely to be the most reactive?

bromine (br)
chlorine (cl)
fluorine (f)
iodine (i)

Explanation:

Bromine (Br), chlorine (Cl), fluorine (F), and iodine (I) are all halogens. In the halogen group (Group 17 of the periodic table), reactivity decreases as you go down the group. This is because as the atomic radius increases (with more electron shells), the ability to gain an electron (electronegativity) decreases. Fluorine is at the top of the halogen group (has the smallest atomic radius among these), so it has the highest electronegativity and is the most reactive among these halogens.

Answer:

C. fluorine (F)