Question

Which of the following species is isoelectronic with $C{O}_2$?

• A. $N_3^{-}$
• B. $(CNO{)}^{-}$
• C. $(NCN{)}^{2-}$
• D. All of these

Answer 1

The correct option is D All of these

Isoelectronic species are those which have an equal number of electrons.

$C{O}_2$ has $6+8+8=22$ electrons.

$\left(a\right)$ Nitrogen atoms have $7$ electrons each. Hence in the case of azide ion, we have $3$ atoms of N that contain a total of $21$ electrons and it has a charge of $-1$ on it. So adding it, we get a total of $22$ electrons.

$\left(b\right)$ The number of electrons in $C,N$ and $O$ are $6,7$ and $8$ respectively. In total, there are 21 electrons. With a negative charge on it, the total number of electrons comes to $22$.

$\left(c\right)$ The number of electrons in $C\&N$ are $6\&7$ respectively. Hence, in $(NCN{)}^{2-}$ there are 22 electrons.

All the given ions have the same number of electrons, that is, $22$.

Hence all the species are isoelectronic with $C{O}_2$.