Question

Which of the following species has four lone pairs of electrons in its outer shell ?

• A. $I$
• B. $O^{-}$
• C. $C{l}^{-}$
• D. $He$

Answer 1

Answer: (C)

$C{l}^{-}$

Consider the electronic configuration of each of these options:-

A) $I$ - $\left[Kr\right]4d^{10}5s^{2}5p^5\to$ 3 lone pairs.

B) $O^{-}$ - $1s^{2}2s^{2}2p^5\to$ 3 lone pairs.

C) $C{l}^{-}$ - $1s^{2}2s^{2}2p^{6}3s^{2}3p^6\to$ 4 lone pairs.

D) $He$ - $1s^2\to$ 1 lone pair.

Hence option C is the right answer.