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)

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