Which electronic configuration of an element has abnormally high difference between second and third ionization energy ?

Options

(a) I s², 2s², 2p⁶, 3s¹
(b) I s², 2 s², 2 p⁶, 3s¹ 3 p¹
(c) I s², 2 s², 2 p⁶, 3s² 3 p²
(d) I s², 2s², 2p⁶, 3s²

Correct Answer:

I s², 2s², 2p⁶, 3s²

Explanation:

Abnormally high difference between 2nd and3rd ionization energy means that the elementhas two valence electrons, i.e., configuration(d)