Question

Which one is most reactive element?

• A. $F$
• B. $Cl$
• C. $Br$
• D. $I$

Answer 1

The correct option is A

$\mathrm{F}$

Introduction:

The chemical property of the elements in same group are same but the chemical reactivity differs.

Explanation for the correct option:

In a group, the metal reactivity rises top to bottom.

But in halogens of group 17, the reactivity decreases down the group. This is due to increase in atomic radii and electronic energy levels.

The given elements Fluorine ($\mathrm{F}$), Chlorine ($\mathrm{Cl}$), Bromine ($\mathrm{Br}$) and Iodine ($\mathrm{I}$) belong to same group 17.

Fluorine is more reactive than other elements.

Explanation for the incorrect option:

Chlorine, Bromine and Iodine have lesser reactivity because of the higher electronic energy levels, the valence electrons attraction downs.

Final answer:

Hence, option (A) is the correct option.