An ion has 18 electrons in the outermost shell, it is

Options

(a) Cu⁺
(b) Th⁴⁺
(c) Cs⁺
(d) K⁺

Correct Answer:

Cu⁺

Explanation:

Cu⁺ = 29 -1 electrons
Electronic configuration – 1s² 2s² 2p⁶ {3s² 3p⁶ 3d¹⁰}.