Question

Which one of the following elements is most reactive?

• A. Fluorine
• B. Argon
• C. Helium
• D. Radon

Answer 1

The correct option is A

Fluorine

Explanation for correct option

(A) Florine

Chemical Reactivity

• The reactivity of an atom is determined by the number of electrons in its outermost shell.
• Reactivity decreases across a period and increases down the group in the periodic table.

Florine

• Since they rapidly obtain an electron to fill their outermost shell, halogens are extremely reactive.
• An atom's ability to attract a shared pair of electrons is known as electronegativity.
• Fluorine $\left(\mathrm{F}\right)$ is more reactive than chlorine because it has a greater electronegativity.
• Noble gases have complete electron shells, and they have low reactivity.

Explanation for incorrect options

• The most reactive is Florine.
• Hence all other options (B), (C) and (D) are incorrect.

Therefore, the correct option is (A) Florine.