Question

The number of s-electrons present in an ion with 55 protons in its unipositive state is

(1) 8

(2) 9

(3) 12

(4) 10

Answer 1

Correct option is (4) 10

Z = 55 [Cs] ⇒ [Xe] 6s¹

[Cs⁺] ⇒ [Xe] i.e. upto 5s count e^– of s-subshell

i.e. 1s, 2s, 3s, 4s, 5s ⇒ 10 electrons