Question

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

• A. 8
• B. 12
• C. 9
• D. 10

Answer 1

Answer: (D)

$Z =55[ Cs ] \Rightarrow[ Xe ] 6 s ^1$
$\left[ Cs ^{+}\right] \Rightarrow[ Xe ]$ i.e. upto $5 s$ count $e ^{-}$of s-subshell
i.e. $1 s , 2 s , 3 s , 4 s , 5 s \Rightarrow 10$ electrons